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2022-04-25selftests/bpf: Add C tests for kptrKumar Kartikeya Dwivedi
This uses the __kptr and __kptr_ref macros as well, and tries to test the stuff that is supposed to work, since we have negative tests in test_verifier suite. Also include some code to test map-in-map support, such that the inner_map_meta matches the kptr_off_tab of map added as element. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-12-memxor@gmail.com
2022-04-25libbpf: Add kptr type tag macros to bpf_helpers.hKumar Kartikeya Dwivedi
Include convenience definitions: __kptr: Unreferenced kptr __kptr_ref: Referenced kptr Users can use them to tag the pointer type meant to be used with the new support directly in the map value definition. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-11-memxor@gmail.com
2022-04-25bpf: Make BTF type match stricter for release argumentsKumar Kartikeya Dwivedi
The current of behavior of btf_struct_ids_match for release arguments is that when type match fails, it retries with first member type again (recursively). Since the offset is already 0, this is akin to just casting the pointer in normal C, since if type matches it was just embedded inside parent sturct as an object. However, we want to reject cases for release function type matching, be it kfunc or BPF helpers. An example is the following: struct foo { struct bar b; }; struct foo *v = acq_foo(); rel_bar(&v->b); // btf_struct_ids_match fails btf_types_are_same, then // retries with first member type and succeeds, while // it should fail. Hence, don't walk the struct and only rely on btf_types_are_same for strict mode. All users of strict mode must be dealing with zero offset anyway, since otherwise they would want the struct to be walked. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-10-memxor@gmail.com
2022-04-25bpf: Teach verifier about kptr_get kfunc helpersKumar Kartikeya Dwivedi
We introduce a new style of kfunc helpers, namely *_kptr_get, where they take pointer to the map value which points to a referenced kernel pointer contained in the map. Since this is referenced, only bpf_kptr_xchg from BPF side and xchg from kernel side is allowed to change the current value, and each pointer that resides in that location would be referenced, and RCU protected (this must be kept in mind while adding kernel types embeddable as reference kptr in BPF maps). This means that if do the load of the pointer value in an RCU read section, and find a live pointer, then as long as we hold RCU read lock, it won't be freed by a parallel xchg + release operation. This allows us to implement a safe refcount increment scheme. Hence, enforce that first argument of all such kfunc is a proper PTR_TO_MAP_VALUE pointing at the right offset to referenced pointer. For the rest of the arguments, they are subjected to typical kfunc argument checks, hence allowing some flexibility in passing more intent into how the reference should be taken. For instance, in case of struct nf_conn, it is not freed until RCU grace period ends, but can still be reused for another tuple once refcount has dropped to zero. Hence, a bpf_ct_kptr_get helper not only needs to call refcount_inc_not_zero, but also do a tuple match after incrementing the reference, and when it fails to match it, put the reference again and return NULL. This can be implemented easily if we allow passing additional parameters to the bpf_ct_kptr_get kfunc, like a struct bpf_sock_tuple * and a tuple__sz pair. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-9-memxor@gmail.com
2022-04-25bpf: Wire up freeing of referenced kptrKumar Kartikeya Dwivedi
A destructor kfunc can be defined as void func(type *), where type may be void or any other pointer type as per convenience. In this patch, we ensure that the type is sane and capture the function pointer into off_desc of ptr_off_tab for the specific pointer offset, with the invariant that the dtor pointer is always set when 'kptr_ref' tag is applied to the pointer's pointee type, which is indicated by the flag BPF_MAP_VALUE_OFF_F_REF. Note that only BTF IDs whose destructor kfunc is registered, thus become the allowed BTF IDs for embedding as referenced kptr. Hence it serves the purpose of finding dtor kfunc BTF ID, as well acting as a check against the whitelist of allowed BTF IDs for this purpose. Finally, wire up the actual freeing of the referenced pointer if any at all available offsets, so that no references are leaked after the BPF map goes away and the BPF program previously moved the ownership a referenced pointer into it. The behavior is similar to BPF timers, where bpf_map_{update,delete}_elem will free any existing referenced kptr. The same case is with LRU map's bpf_lru_push_free/htab_lru_push_free functions, which are extended to reset unreferenced and free referenced kptr. Note that unlike BPF timers, kptr is not reset or freed when map uref drops to zero. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-8-memxor@gmail.com
2022-04-25bpf: Populate pairs of btf_id and destructor kfunc in btfKumar Kartikeya Dwivedi
To support storing referenced PTR_TO_BTF_ID in maps, we require associating a specific BTF ID with a 'destructor' kfunc. This is because we need to release a live referenced pointer at a certain offset in map value from the map destruction path, otherwise we end up leaking resources. Hence, introduce support for passing an array of btf_id, kfunc_btf_id pairs that denote a BTF ID and its associated release function. Then, add an accessor 'btf_find_dtor_kfunc' which can be used to look up the destructor kfunc of a certain BTF ID. If found, we can use it to free the object from the map free path. The registration of these pairs also serve as a whitelist of structures which are allowed as referenced PTR_TO_BTF_ID in a BPF map, because without finding the destructor kfunc, we will bail and return an error. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-7-memxor@gmail.com
2022-04-25bpf: Adapt copy_map_value for multiple offset caseKumar Kartikeya Dwivedi
Since now there might be at most 10 offsets that need handling in copy_map_value, the manual shuffling and special case is no longer going to work. Hence, let's generalise the copy_map_value function by using a sorted array of offsets to skip regions that must be avoided while copying into and out of a map value. When the map is created, we populate the offset array in struct map, Then, copy_map_value uses this sorted offset array is used to memcpy while skipping timer, spin lock, and kptr. The array is allocated as in most cases none of these special fields would be present in map value, hence we can save on space for the common case by not embedding the entire object inside bpf_map struct. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-6-memxor@gmail.com
2022-04-25bpf: Prevent escaping of kptr loaded from mapsKumar Kartikeya Dwivedi
While we can guarantee that even for unreferenced kptr, the object pointer points to being freed etc. can be handled by the verifier's exception handling (normal load patching to PROBE_MEM loads), we still cannot allow the user to pass these pointers to BPF helpers and kfunc, because the same exception handling won't be done for accesses inside the kernel. The same is true if a referenced pointer is loaded using normal load instruction. Since the reference is not guaranteed to be held while the pointer is used, it must be marked as untrusted. Hence introduce a new type flag, PTR_UNTRUSTED, which is used to mark all registers loading unreferenced and referenced kptr from BPF maps, and ensure they can never escape the BPF program and into the kernel by way of calling stable/unstable helpers. In check_ptr_to_btf_access, the !type_may_be_null check to reject type flags is still correct, as apart from PTR_MAYBE_NULL, only MEM_USER, MEM_PERCPU, and PTR_UNTRUSTED may be set for PTR_TO_BTF_ID. The first two are checked inside the function and rejected using a proper error message, but we still want to allow dereference of untrusted case. Also, we make sure to inherit PTR_UNTRUSTED when chain of pointers are walked, so that this flag is never dropped once it has been set on a PTR_TO_BTF_ID (i.e. trusted to untrusted transition can only be in one direction). In convert_ctx_accesses, extend the switch case to consider untrusted PTR_TO_BTF_ID in addition to normal PTR_TO_BTF_ID for PROBE_MEM conversion for BPF_LDX. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-5-memxor@gmail.com
2022-04-25bpf: Allow storing referenced kptr in mapKumar Kartikeya Dwivedi
Extending the code in previous commits, introduce referenced kptr support, which needs to be tagged using 'kptr_ref' tag instead. Unlike unreferenced kptr, referenced kptr have a lot more restrictions. In addition to the type matching, only a newly introduced bpf_kptr_xchg helper is allowed to modify the map value at that offset. This transfers the referenced pointer being stored into the map, releasing the references state for the program, and returning the old value and creating new reference state for the returned pointer. Similar to unreferenced pointer case, return value for this case will also be PTR_TO_BTF_ID_OR_NULL. The reference for the returned pointer must either be eventually released by calling the corresponding release function, otherwise it must be transferred into another map. It is also allowed to call bpf_kptr_xchg with a NULL pointer, to clear the value, and obtain the old value if any. BPF_LDX, BPF_STX, and BPF_ST cannot access referenced kptr. A future commit will permit using BPF_LDX for such pointers, but attempt at making it safe, since the lifetime of object won't be guaranteed. There are valid reasons to enforce the restriction of permitting only bpf_kptr_xchg to operate on referenced kptr. The pointer value must be consistent in face of concurrent modification, and any prior values contained in the map must also be released before a new one is moved into the map. To ensure proper transfer of this ownership, bpf_kptr_xchg returns the old value, which the verifier would require the user to either free or move into another map, and releases the reference held for the pointer being moved in. In the future, direct BPF_XCHG instruction may also be permitted to work like bpf_kptr_xchg helper. Note that process_kptr_func doesn't have to call check_helper_mem_access, since we already disallow rdonly/wronly flags for map, which is what check_map_access_type checks, and we already ensure the PTR_TO_MAP_VALUE refers to kptr by obtaining its off_desc, so check_map_access is also not required. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-4-memxor@gmail.com
2022-04-25NFSv4: Don't invalidate inode attributes on delegation returnTrond Myklebust
There is no need to declare attributes such as the ctime, mtime and block size invalid when we're just returning a delegation, so it is inappropriate to call nfs_post_op_update_inode_force_wcc(). Instead, just call nfs_refresh_inode() after faking up the change attribute. We know that the GETATTR op occurs before the DELEGRETURN, so we are safe when doing this. Fixes: 0bc2c9b4dca9 ("NFSv4: Don't discard the attributes returned by asynchronous DELEGRETURN") Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
2022-04-25bpf: Tag argument to be released in bpf_func_protoKumar Kartikeya Dwivedi
Add a new type flag for bpf_arg_type that when set tells verifier that for a release function, that argument's register will be the one for which meta.ref_obj_id will be set, and which will then be released using release_reference. To capture the regno, introduce a new field release_regno in bpf_call_arg_meta. This would be required in the next patch, where we may either pass NULL or a refcounted pointer as an argument to the release function bpf_kptr_xchg. Just releasing only when meta.ref_obj_id is set is not enough, as there is a case where the type of argument needed matches, but the ref_obj_id is set to 0. Hence, we must enforce that whenever meta.ref_obj_id is zero, the register that is to be released can only be NULL for a release function. Since we now indicate whether an argument is to be released in bpf_func_proto itself, is_release_function helper has lost its utitlity, hence refactor code to work without it, and just rely on meta.release_regno to know when to release state for a ref_obj_id. Still, the restriction of one release argument and only one ref_obj_id passed to BPF helper or kfunc remains. This may be lifted in the future. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-3-memxor@gmail.com
2022-04-25bpf: Allow storing unreferenced kptr in mapKumar Kartikeya Dwivedi
This commit introduces a new pointer type 'kptr' which can be embedded in a map value to hold a PTR_TO_BTF_ID stored by a BPF program during its invocation. When storing such a kptr, BPF program's PTR_TO_BTF_ID register must have the same type as in the map value's BTF, and loading a kptr marks the destination register as PTR_TO_BTF_ID with the correct kernel BTF and BTF ID. Such kptr are unreferenced, i.e. by the time another invocation of the BPF program loads this pointer, the object which the pointer points to may not longer exist. Since PTR_TO_BTF_ID loads (using BPF_LDX) are patched to PROBE_MEM loads by the verifier, it would safe to allow user to still access such invalid pointer, but passing such pointers into BPF helpers and kfuncs should not be permitted. A future patch in this series will close this gap. The flexibility offered by allowing programs to dereference such invalid pointers while being safe at runtime frees the verifier from doing complex lifetime tracking. As long as the user may ensure that the object remains valid, it can ensure data read by it from the kernel object is valid. The user indicates that a certain pointer must be treated as kptr capable of accepting stores of PTR_TO_BTF_ID of a certain type, by using a BTF type tag 'kptr' on the pointed to type of the pointer. Then, this information is recorded in the object BTF which will be passed into the kernel by way of map's BTF information. The name and kind from the map value BTF is used to look up the in-kernel type, and the actual BTF and BTF ID is recorded in the map struct in a new kptr_off_tab member. For now, only storing pointers to structs is permitted. An example of this specification is shown below: #define __kptr __attribute__((btf_type_tag("kptr"))) struct map_value { ... struct task_struct __kptr *task; ... }; Then, in a BPF program, user may store PTR_TO_BTF_ID with the type task_struct into the map, and then load it later. Note that the destination register is marked PTR_TO_BTF_ID_OR_NULL, as the verifier cannot know whether the value is NULL or not statically, it must treat all potential loads at that map value offset as loading a possibly NULL pointer. Only BPF_LDX, BPF_STX, and BPF_ST (with insn->imm = 0 to denote NULL) are allowed instructions that can access such a pointer. On BPF_LDX, the destination register is updated to be a PTR_TO_BTF_ID, and on BPF_STX, it is checked whether the source register type is a PTR_TO_BTF_ID with same BTF type as specified in the map BTF. The access size must always be BPF_DW. For the map in map support, the kptr_off_tab for outer map is copied from the inner map's kptr_off_tab. It was chosen to do a deep copy instead of introducing a refcount to kptr_off_tab, because the copy only needs to be done when paramterizing using inner_map_fd in the map in map case, hence would be unnecessary for all other users. It is not permitted to use MAP_FREEZE command and mmap for BPF map having kptrs, similar to the bpf_timer case. A kptr also requires that BPF program has both read and write access to the map (hence both BPF_F_RDONLY_PROG and BPF_F_WRONLY_PROG are disallowed). Note that check_map_access must be called from both check_helper_mem_access and for the BPF instructions, hence the kptr check must distinguish between ACCESS_DIRECT and ACCESS_HELPER, and reject ACCESS_HELPER cases. We rename stack_access_src to bpf_access_src and reuse it for this purpose. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220424214901.2743946-2-memxor@gmail.com
2022-04-25bpf: Use bpf_prog_run_array_cg_flags everywhereStanislav Fomichev
Rename bpf_prog_run_array_cg_flags to bpf_prog_run_array_cg and use it everywhere. check_return_code already enforces sane return ranges for all cgroup types. (only egress and bind hooks have uncanonical return ranges, the rest is using [0, 1]) No functional changes. v2: - 'func_ret & 1' under explicit test (Andrii & Martin) Suggested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220425220448.3669032-1-sdf@google.com
2022-04-25Merge tag 'sunxi-clk-fixes-for-5.18-2' of ↵Stephen Boyd
https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux into clk-fixes Pull Allwinner clk fixes from Jernej Skrabec: - Add missing sentinel - check return value for platform_get_resource() - mark rtc-32k as critical * tag 'sunxi-clk-fixes-for-5.18-2' of https://git.kernel.org/pub/scm/linux/kernel/git/sunxi/linux: clk: sunxi: sun9i-mmc: check return value after calling platform_get_resource() clk: sunxi-ng: sun6i-rtc: Mark rtc-32k as critical clk: sunxi-ng: fix not NULL terminated coccicheck error
2022-04-25bpftool, musl compat: Replace sys/fcntl.h by fcntl.hDominique Martinet
musl does not like including sys/fcntl.h directly: [...] 1 | #warning redirecting incorrect #include <sys/fcntl.h> to <fcntl.h> [...] Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20220424051022.2619648-5-asmadeus@codewreck.org
2022-04-25bpftool, musl compat: Replace nftw with FTW_ACTIONRETVALDominique Martinet
musl nftw implementation does not support FTW_ACTIONRETVAL. There have been multiple attempts at pushing the feature in musl upstream, but it has been refused or ignored all the times: https://www.openwall.com/lists/musl/2021/03/26/1 https://www.openwall.com/lists/musl/2022/01/22/1 In this case we only care about /proc/<pid>/fd/<fd>, so it's not too difficult to reimplement directly instead, and the new implementation makes 'bpftool perf' slightly faster because it doesn't needlessly stat/readdir unneeded directories (54ms -> 13ms on my machine). Signed-off-by: Dominique Martinet <asmadeus@codewreck.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20220424051022.2619648-4-asmadeus@codewreck.org
2022-04-25wwan_hwsim: Avoid flush_scheduled_work() usageTetsuo Handa
Flushing system-wide workqueues is dangerous and will be forbidden. Replace system_wq with local wwan_wq. While we are at it, make err_clean_devs: label of wwan_hwsim_init() behave like wwan_hwsim_exit(), for it is theoretically possible to call wwan_hwsim_debugfs_devcreate_write()/wwan_hwsim_debugfs_devdestroy_write() by the moment wwan_hwsim_init_devs() returns. Link: https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com> Reviewed-by: Loic Poulain <loic.poulain@linaro.org> Link: https://lore.kernel.org/r/7390d51f-60e2-3cee-5277-b819a55ceabe@I-love.SAKURA.ne.jp Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-25net: ieee802154: ca8210: Call _xmit_error() when a transmission failsMiquel Raynal
ieee802154_xmit_error() is the right helper to call when a transmission has failed. Let's use it instead of open-coding it. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-11-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: ieee802154: ca8210: Use core return codes instead of hardcoding themMiquel Raynal
All the error codes defined in this driver are generic and already defined in the ieee802154 main header. Let's just get rid of these extra definition and switch to the core's values. There is no functional change. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-10-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: ieee802154: atusb: Call _xmit_hw_error() upon transmission errorMiquel Raynal
ieee802154_xmit_hw_error() is the right helper to call when a transmission has failed for a non-determined (and probably not IEEE802.15.4 specific) reason. Let's use this helper instead of open-coding it. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-9-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: ieee802154: at86rf230: Forward Tx trac errorsMiquel Raynal
Commit 493bc90a9683 ("at86rf230: add debugfs support") brought trac support as part of a debugfs feature, in order to add some testing capabilities involving ack handling. As we want to collect trac errors but do not need the debugfs feature anymore, let's partially revert this commit, keeping the Tx trac handling part which still makes sense. This allows to always return the trac error directly to the core with the recently introduced ieee802154_xmit_error() helper. Suggested-by: Alexander Aring <alex.aring@gmail.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-8-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: ieee802154: at86rf230: Call _xmit_hw_error() when failing to offload framesMiquel Raynal
If we end up at this location, it means that there was likely a hardware issue (either a bus error when asynchronously offloading the packet to the transceiver, or the transceiver took too long for some state change). In this case it was decided to return IEEE802154_SYSTEM_ERROR through the ieee802154_xmit_hw_error() helper dedicated to non IEEE802.15.4 specific errors. Let's use this helper instead of (almost) open-coding it. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-7-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: mac802154: Create an error helper for asynchronous offloading errorsMiquel Raynal
A few drivers do the full transmit operation asynchronously, which means that a bus error that happens when forwarding the packet to the transmitter or a timeout happening when offloading the request to the transmitter will not be reported immediately. The solution in this case is to call this new helper to free the necessary resources, restart the queue and always return the same generic TRAC error code: IEEE802154_SYSTEM_ERROR. Suggested-by: Alexander Aring <alex.aring@gmail.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-6-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: mac802154: Create an offloaded transmission error helperMiquel Raynal
So far there is only a helper for successful transmissions, which led device drivers to implement their own handling in case of error. Unfortunately, we really need all the drivers to give the hand back to the core once they are done in order to be able to build a proper synchronous API. So let's create a _xmit_error() helper and take this opportunity to fill the new device-global field storing Tx statuses. Suggested-by: Alexander Aring <alex.aring@gmail.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-5-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: mac802154: Save a global error code on transmissionsMiquel Raynal
So far no error is returned from a failing transmission. However it might sometimes be useful, and particularly easy to use during sync transfers (for certain MLME commands). Let's create an internal variable for that, global to the device. Right now only success are registered, which is rather useless, but soon we will have more situations filling this field. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-4-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: ieee802154: Fill the list of MLME return codesMiquel Raynal
There are more codes than already listed, let's be a bit more exhaustive. This will allow to drop device drivers local definitions of these codes. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-3-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25net: ieee802154: Enhance/fix the names of the MLME return codesMiquel Raynal
Let's keep these definitions as close to the specification as possible while they are not yet in use. The names get slightly longer, but we gain the minor cost of being able to search the spec more easily. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Acked-by: Alexander Aring <aahringo@redhat.com> Link: https://lore.kernel.org/r/20220407100903.1695973-2-miquel.raynal@bootlin.com Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
2022-04-25video: fbdev: clps711x-fb: Use syscon_regmap_lookup_by_phandleAlexander Shiyan
Since version 5.13, the standard syscon bindings have been added to all clps711x DT nodes, so we can now use the more general syscon_regmap_lookup_by_phandle function to get the syscon pointer. Signed-off-by: Alexander Shiyan <eagle.alexander923@gmail.com> Signed-off-by: Helge Deller <deller@gmx.de>
2022-04-25Merge branch 'net-smc-two-fixes-for-smc-fallback'Jakub Kicinski
Wen Gu says: ==================== net/smc: Two fixes for smc fallback This patch set includes two fixes for smc fallback: Patch 1/2 introduces some simple helpers to wrap the replacement and restore of clcsock's callback functions. Make sure that only the original callbacks will be saved and not overwritten. Patch 2/2 fixes a syzbot reporting slab-out-of-bound issue where smc_fback_error_report() accesses the already freed smc sock (see https://lore.kernel.org/r/00000000000013ca8105d7ae3ada@google.com/). The patch fixes it by resetting sk_user_data and restoring clcsock callback functions timely in fallback situation. But it should be noted that although patch 2/2 can fix the issue of 'slab-out-of-bounds/use-after-free in smc_fback_error_report', it can't pass the syzbot reproducer test. Because after applying these two patches in upstream, syzbot reproducer triggered another known issue like this: ================================================================== BUG: KASAN: use-after-free in tcp_retransmit_timer+0x2ef3/0x3360 net/ipv4/tcp_timer.c:511 Read of size 8 at addr ffff888020328380 by task udevd/4158 CPU: 1 PID: 4158 Comm: udevd Not tainted 5.18.0-rc3-syzkaller-00074-gb05a5683eba6-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313 print_report mm/kasan/report.c:429 [inline] kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 tcp_retransmit_timer+0x2ef3/0x3360 net/ipv4/tcp_timer.c:511 tcp_write_timer_handler+0x5e6/0xbc0 net/ipv4/tcp_timer.c:622 tcp_write_timer+0xa2/0x2b0 net/ipv4/tcp_timer.c:642 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x679/0xa80 kernel/time/timer.c:1737 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1750 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 </IRQ> ... (detail report can be found in https://syzkaller.appspot.com/text?tag=CrashReport&x=15406b44f00000) IMHO, the above issue is the same as this known one: https://syzkaller.appspot.com/bug?extid=694120e1002c117747ed, and it doesn't seem to be related with SMC. The discussion about this known issue is ongoing and can be found in https://lore.kernel.org/bpf/000000000000f75af905d3ba0716@google.com/T/. And I added the temporary solution mentioned in the above discussion on top of my two patches, the syzbot reproducer of 'slab-out-of-bounds/ use-after-free in smc_fback_error_report' no longer triggers any issue. ==================== Link: https://lore.kernel.org/r/1650614179-11529-1-git-send-email-guwen@linux.alibaba.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-25net/smc: Fix slab-out-of-bounds issue in fallbackWen Gu
syzbot reported a slab-out-of-bounds/use-after-free issue, which was caused by accessing an already freed smc sock in fallback-specific callback functions of clcsock. This patch fixes the issue by restoring fallback-specific callback functions to original ones and resetting clcsock sk_user_data to NULL before freeing smc sock. Meanwhile, this patch introduces sk_callback_lock to make the access and assignment to sk_user_data mutually exclusive. Reported-by: syzbot+b425899ed22c6943e00b@syzkaller.appspotmail.com Fixes: 341adeec9ada ("net/smc: Forward wakeup to smc socket waitqueue after fallback") Link: https://lore.kernel.org/r/00000000000013ca8105d7ae3ada@google.com/ Signed-off-by: Wen Gu <guwen@linux.alibaba.com> Acked-by: Karsten Graul <kgraul@linux.ibm.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-25net/smc: Only save the original clcsock callback functionsWen Gu
Both listen and fallback process will save the current clcsock callback functions and establish new ones. But if both of them happen, the saved callback functions will be overwritten. So this patch introduces some helpers to ensure that only save the original callback functions of clcsock. Fixes: 341adeec9ada ("net/smc: Forward wakeup to smc socket waitqueue after fallback") Signed-off-by: Wen Gu <guwen@linux.alibaba.com> Acked-by: Karsten Graul <kgraul@linux.ibm.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-04-25Merge tag 'f2fs-fix-5.18' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs Pull f2fs fixes from Jaegeuk Kim: "This includes major bug fixes introduced in 5.18-rc1 and 5.17+: - Remove obsolete whint_mode (5.18-rc1) - Fix IO split issue caused by op_flags change in f2fs (5.18-rc1) - Fix a wrong condition check to detect IO failure loop (5.18-rc1) - Fix wrong data truncation during roll-forward (5.17+)" * tag 'f2fs-fix-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: f2fs: should not truncate blocks during roll-forward recovery f2fs: fix wrong condition check when failing metapage read f2fs: keep io_flags to avoid IO split due to different op_flags in two fio holders f2fs: remove obsolete whint_mode
2022-04-25clk: sunxi: sun9i-mmc: check return value after calling platform_get_resource()Yang Yingliang
It will cause null-ptr-deref if platform_get_resource() returns NULL, we need check the return value. Fixes: 7a6fca879f59 ("clk: sunxi: Add driver for A80 MMC config clocks/resets") Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Reviewed-by: Samuel Holland <samuel@sholland.org> Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com> Link: https://lore.kernel.org/r/20220421134308.2885094-1-yangyingliang@huawei.com
2022-04-25bus: sunxi-rsb: Fix the return value of sunxi_rsb_device_create()Christophe JAILLET
This code is really spurious. It always returns an ERR_PTR, even when err is known to be 0 and calls put_device() after a successful device_register() call. It is likely that the return statement in the normal path is missing. Add 'return rdev;' to fix it. Fixes: d787dcdb9c8f ("bus: sunxi-rsb: Add driver for Allwinner Reduced Serial Bus") Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Samuel Holland <samuel@sholland.org> Tested-by: Samuel Holland <samuel@sholland.org> Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com> Link: https://lore.kernel.org/r/ef2b9576350bba4c8e05e669e9535e9e2a415763.1650551719.git.christophe.jaillet@wanadoo.fr
2022-04-25no-MMU: expose vmalloc_huge() for alloc_large_system_hash()Linus Torvalds
It turns out that for the CONFIG_MMU=n builds, vmalloc_huge() was never defined, since it's defined in mm/vmalloc.c, which doesn't get built for the no-MMU configurations. Just implement the trivial wrapper for the no-MMU case too. In fact, just make it an alias to the existing __vmalloc() function that has the same signature. Link: https://lore.kernel.org/all/CAMuHMdVdx2V1uhv_152Sw3_z2xE0spiaWp1d6Ko8-rYmAxUBAg@mail.gmail.com/ Link: https://lore.kernel.org/all/CA+G9fYscb1y4a17Sf5G_Aibt+WuSf-ks_Qjw9tYFy=A4sjCEug@mail.gmail.com/ Link: https://lore.kernel.org/all/20220425150356.GA4138752@roeck-us.net/ Reported-and-tested-by: Linux Kernel Functional Testing <lkft@linaro.org> Reported-and-tested-by: Geert Uytterhoeven <geert@linux-m68k.org> Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-04-25hwmon: (pmbus) disable PEC if not enabledAdam Wujek
Explicitly disable PEC when the client does not support it. The problematic scenario is the following. A device with enabled PEC support is up and running and a kernel driver is loaded. Then the driver is unloaded (or device unbound), the HW device is reconfigured externally (e.g. by i2cset) to advertise itself as not supporting PEC. Without a new code, at the second load of the driver (or bind) the "flags" variable is not updated to avoid PEC usage. As a consequence the further communication with the device is done with the PEC enabled, which is wrong and may fail. The implementation first disable the I2C_CLIENT_PEC flag, then the old code enable it if needed. Fixes: 4e5418f787ec ("hwmon: (pmbus_core) Check adapter PEC support") Signed-off-by: Adam Wujek <dev_public@wujek.eu> Link: https://lore.kernel.org/r/20220420145059.431061-1-dev_public@wujek.eu Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2022-04-25libbpf: Remove unnecessary type castYuntao Wang
The link variable is already of type 'struct bpf_link *', casting it to 'struct bpf_link *' is redundant, drop it. Signed-off-by: Yuntao Wang <ytcoode@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20220424143420.457082-1-ytcoode@gmail.com
2022-04-25Documentation: siphash: disambiguate HalfSipHash algorithm from hsiphash ↵Eric Biggers
functions Fix the documentation for the hsiphash functions to avoid conflating the HalfSipHash algorithm with the hsiphash functions, since these functions actually implement either HalfSipHash or SipHash, and random.c now uses HalfSipHash (in a very special way) without the hsiphash functions. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-04-25Documentation: siphash: enclose HalfSipHash usage example in the literal blockBagas Sanjaya
Render usage example of HalfSipHash function as code block by using literal block syntax. Cc: Jonathan Corbet <corbet@lwn.net> Cc: Eric Biggers <ebiggers@google.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-04-25Documentation: siphash: convert danger note to warning for HalfSipHashBagas Sanjaya
Render danger paragraph into warning block for emphasization. Cc: Jonathan Corbet <corbet@lwn.net> Cc: Eric Biggers <ebiggers@google.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-04-25random: document crng_fast_key_erasure() destination possibilityJason A. Donenfeld
This reverts 35a33ff3807d ("random: use memmove instead of memcpy for remaining 32 bytes"), which was made on a totally bogus basis. The thing it was worried about overlapping came from the stack, not from one of its arguments, as Eric pointed out. But the fact that this confusion even happened draws attention to the fact that it's a bit non-obvious that the random_data parameter can alias chacha_state, and in fact should do so when the caller can't rely on the stack being cleared in a timely manner. So this commit documents that. Reported-by: Eric Biggers <ebiggers@kernel.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-04-25ASoC: dmaengine: Restore NULL prepare_slave_config() callbackCodrin Ciubotariu
As pointed out by Sascha Hauer, this patch changes: if (pmc->config && !pcm->config->prepare_slave_config) <do nothing> to: if (pmc->config && !pcm->config->prepare_slave_config) snd_dmaengine_pcm_prepare_slave_config() This breaks the drivers that do not need a call to dmaengine_slave_config(). Drivers that still need to call snd_dmaengine_pcm_prepare_slave_config(), but have a NULL pcm->config->prepare_slave_config should use snd_dmaengine_pcm_prepare_slave_config() as their prepare_slave_config callback. Fixes: 9a1e13440a4f ("ASoC: dmaengine: do not use a NULL prepare_slave_config() callback") Reported-by: Sascha Hauer <sha@pengutronix.de> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com> Link: https://lore.kernel.org/r/20220421125403.2180824-1-codrin.ciubotariu@microchip.com Signed-off-by: Mark Brown <broonie@kernel.org>
2022-04-25ASoC: atmel: mchp-pdmc: set prepare_slave_configCodrin Ciubotariu
Since a pointer to struct snd_dmaengine_pcm_config is passed, snd_dmaengine_pcm_prepare_slave_config() is no longer called unless it's explicitly set in prepare_slave_config. Fixes: 50291652af52 ("ASoC: atmel: mchp-pdmc: add PDMC driver") Suggested-by: Sascha Hauer <sha@pengutronix.de> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com> Link: https://lore.kernel.org/r/20220421125403.2180824-2-codrin.ciubotariu@microchip.com Signed-off-by: Mark Brown <broonie@kernel.org>
2022-04-25ASoC: max98090: Generate notifications on changes for custom controlMark Brown
The max98090 driver has some custom controls which share a put() function which returns 0 unconditionally, meaning that events are not generated when the value changes. Fix that. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20220420193454.2647908-2-broonie@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2022-04-25ASoC: max98090: Reject invalid values in custom control put()Mark Brown
The max98090 driver has a custom put function for some controls which can only be updated in certain circumstances which makes no effort to validate that input is suitable for the control, allowing out of spec values to be written to the hardware and presented to userspace. Fix this by returning an error when invalid values are written. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20220420193454.2647908-1-broonie@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org>
2022-04-25wireless: add plfxlc driver for pureLiFi X, XL, XC devicesSrinivasan Raju
This is a driver for pureLiFi X, XL, XC devices which use light to transmit data, so they are not compatible with normal Wi-Fi devices. The driver uses separate NL80211_BAND_LC band to distinguish from Wi-Fi. The driver is based on 802.11 softMAC Architecture and uses native 802.11 for configuration and management. Station and Ad-Hoc modes are supported. The driver is compiled and tested in ARM, x86 architectures and compiled in powerpc architecture. This driver implementation has been based on the zd1211rw driver. Signed-off-by: Srinivasan Raju <srini.raju@purelifi.com> Signed-off-by: Kalle Valo <kvalo@kernel.org> Link: https://lore.kernel.org/r/20220224182042.132466-3-srini.raju@purelifi.com
2022-04-25Revert "arm64: dts: tegra: Fix boolean properties with values"Arnd Bergmann
This reverts commit 1a67653de0dd, which caused a boot regression. The behavior of the "drive-push-pull" in the kernel does not match what the binding document describes. Revert Rob's patch to make the DT match the kernel again, rather than the binding. Link: https://lore.kernel.org/lkml/YlVAy95eF%2F9b1nmu@orome/ Reported-by: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2022-04-25tcp: make sure treq->af_specific is initializedEric Dumazet
syzbot complained about a recent change in TCP stack, hitting a NULL pointer [1] tcp request sockets have an af_specific pointer, which was used before the blamed change only for SYNACK generation in non SYNCOOKIE mode. tcp requests sockets momentarily created when third packet coming from client in SYNCOOKIE mode were not using treq->af_specific. Make sure this field is populated, in the same way normal TCP requests sockets do in tcp_conn_request(). [1] TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies. Check SNMP counters. general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 1 PID: 3695 Comm: syz-executor864 Not tainted 5.18.0-rc3-syzkaller-00224-g5fd1fe4807f9 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:tcp_create_openreq_child+0xe16/0x16b0 net/ipv4/tcp_minisocks.c:534 Code: 48 c1 ea 03 80 3c 02 00 0f 85 e5 07 00 00 4c 8b b3 28 01 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d 7e 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c9 07 00 00 48 8b 3c 24 48 89 de 41 ff 56 08 48 RSP: 0018:ffffc90000de0588 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff888076490330 RCX: 0000000000000100 RDX: 0000000000000001 RSI: ffffffff87d67ff0 RDI: 0000000000000008 RBP: ffff88806ee1c7f8 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff87d67f00 R11: 0000000000000000 R12: ffff88806ee1bfc0 R13: ffff88801b0e0368 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f517fe58700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffcead76960 CR3: 000000006f97b000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> tcp_v6_syn_recv_sock+0x199/0x23b0 net/ipv6/tcp_ipv6.c:1267 tcp_get_cookie_sock+0xc9/0x850 net/ipv4/syncookies.c:207 cookie_v6_check+0x15c3/0x2340 net/ipv6/syncookies.c:258 tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1131 [inline] tcp_v6_do_rcv+0x1148/0x13b0 net/ipv6/tcp_ipv6.c:1486 tcp_v6_rcv+0x3305/0x3840 net/ipv6/tcp_ipv6.c:1725 ip6_protocol_deliver_rcu+0x2e9/0x1900 net/ipv6/ip6_input.c:422 ip6_input_finish+0x14c/0x2c0 net/ipv6/ip6_input.c:464 NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:473 dst_input include/net/dst.h:461 [inline] ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] ipv6_rcv+0x27f/0x3b0 net/ipv6/ip6_input.c:297 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5405 __netif_receive_skb+0x24/0x1b0 net/core/dev.c:5519 process_backlog+0x3a0/0x7c0 net/core/dev.c:5847 __napi_poll+0xb3/0x6e0 net/core/dev.c:6413 napi_poll net/core/dev.c:6480 [inline] net_rx_action+0x8ec/0xc60 net/core/dev.c:6567 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 Fixes: 5b0b9e4c2c89 ("tcp: md5: incorrect tcp_header_len for incoming connections") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Francesco Ruggeri <fruggeri@arista.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-04-25net: dsa: remove unused headersMarcin Wojtas
Reduce a number of included headers to a necessary minimum. Signed-off-by: Marcin Wojtas <mw@semihalf.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2022-04-25tcp: fix potential xmit stalls caused by TCP_NOTSENT_LOWATEric Dumazet
I had this bug sitting for too long in my pile, it is time to fix it. Thanks to Doug Porter for reminding me of it! We had various attempts in the past, including commit 0cbe6a8f089e ("tcp: remove SOCK_QUEUE_SHRUNK"), but the issue is that TCP stack currently only generates EPOLLOUT from input path, when tp->snd_una has advanced and skb(s) cleaned from rtx queue. If a flow has a big RTT, and/or receives SACKs, it is possible that the notsent part (tp->write_seq - tp->snd_nxt) reaches 0 and no more data can be sent until tp->snd_una finally advances. What is needed is to also check if POLLOUT needs to be generated whenever tp->snd_nxt is advanced, from output path. This bug triggers more often after an idle period, as we do not receive ACK for at least one RTT. tcp_notsent_lowat could be a fraction of what CWND and pacing rate would allow to send during this RTT. In a followup patch, I will remove the bogus call to tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED) from tcp_check_space(). Fact that we have decided to generate an EPOLLOUT does not mean the application has immediately refilled the transmit queue. This optimistic call might have been the reason the bug seemed not too serious. Tested: 200 ms rtt, 1% packet loss, 32 MB tcp_rmem[2] and tcp_wmem[2] $ echo 500000 >/proc/sys/net/ipv4/tcp_notsent_lowat $ cat bench_rr.sh SUM=0 for i in {1..10} do V=`netperf -H remote_host -l30 -t TCP_RR -- -r 10000000,10000 -o LOCAL_BYTES_SENT | egrep -v "MIGRATED|Bytes"` echo $V SUM=$(($SUM + $V)) done echo SUM=$SUM Before patch: $ bench_rr.sh 130000000 80000000 140000000 140000000 140000000 140000000 130000000 40000000 90000000 110000000 SUM=1140000000 After patch: $ bench_rr.sh 430000000 590000000 530000000 450000000 450000000 350000000 450000000 490000000 480000000 460000000 SUM=4680000000 # This is 410 % of the value before patch. Fixes: c9bee3b7fdec ("tcp: TCP_NOTSENT_LOWAT socket option") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Doug Porter <dsp@fb.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Neal Cardwell <ncardwell@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>