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path: root/include/linux/pstore.h
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2017-05-31pstore: Populate pstore record->time fieldKees Cook
The current time will be initially available in the record->time field for all pstore_read() and pstore_write() calls. Backends can either update the field during read(), or use the field during write() instead of fetching time themselves. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Remove write_buf() callbackKees Cook
Now that write() and write_buf() are functionally identical, this removes write_buf(), and renames write_buf_user() to write_user(). Additionally adds sanity-checks for pstore_info's declared functions and flags at registration time. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Replace arguments for write_buf_user() APIKees Cook
Removes argument list in favor of pstore record, though the user buffer remains passed separately since it must carry the __user annotation. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Replace arguments for write_buf() APIKees Cook
As with the other API updates, this removes the long argument list in favor of passing a single pstore recaord. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Replace arguments for erase() APIKees Cook
This removes the argument list for the erase() callback and replaces it with a pointer to the backend record details to be removed. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Replace arguments for write() APIKees Cook
Similar to the pstore_info read() callback, there were too many arguments. This switches to the new struct pstore_record pointer instead. This adds "reason" and "part" to the record structure as well. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Replace arguments for read() APIKees Cook
The argument list for the pstore_read() interface is unwieldy. This changes passes the new struct pstore_record instead. The erst backend was already doing something similar internally. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Extract common arguments into structureKees Cook
The read/mkfile pair pass the same arguments and should be cleared between calls. Move to a structure and wipe it after every loop. Signed-off-by: Kees Cook <keescook@chromium.org>
2017-03-07pstore: Add kernel-doc for struct pstore_infoKees Cook
This adds documentation for struct pstore_info, which also includes the basic API the backends need to implement. Signed-off-by: Kees Cook <keescook@chromium.org>
2016-11-15pstore: Add ftrace timestamp counterJoel Fernandes
In preparation for merging the per CPU buffers into one buffer when we retrieve the pstore ftrace data, we store the timestamp as a counter in the ftrace pstore record. We store the CPU number as well if !PSTORE_CPU_IN_IP, in this case we shift the counter and may lose ordering there but we preserve the same record size. The timestamp counter is also racy, and not doing any locking or synchronization here results in the benefit of lower overhead. Since we don't care much here for exact ordering of function traces across CPUs, we don't synchronize and may lose some counter updates but I'm ok with that. Using trace_clock() results in much lower performance so avoid using it since we don't want accuracy in timestamp and need a rough ordering to perform merge. Signed-off-by: Joel Fernandes <joelaf@google.com> [kees: updated commit message, added comments] Signed-off-by: Kees Cook <keescook@chromium.org>
2016-09-08pstore/pmsg: drop bounce bufferMark Salyzyn
Removing a bounce buffer copy operation in the pmsg driver path is always better. We also gain in overall performance by not requesting a vmalloc on every write as this can cause precious RT tasks, such as user facing media operation, to stall while memory is being reclaimed. Added a write_buf_user to the pstore functions, a backup platform write_buf_user that uses the small buffer that is part of the instance, and implemented a ramoops write_buf_user that only supports PSTORE_TYPE_PMSG. Signed-off-by: Mark Salyzyn <salyzyn@android.com> Signed-off-by: Kees Cook <keescook@chromium.org>
2016-09-08pstore/ram: Set pstore flags dynamicallyNamhyung Kim
The ramoops can be configured to enable each pstore type by setting their size. In that case, it'd be better not to register disabled types in the first place. Cc: Anton Vorontsov <anton@enomsg.org> Cc: Colin Cross <ccross@android.com> Cc: Kees Cook <keescook@chromium.org> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org>
2016-09-08pstore: Split pstore fragile flagsNamhyung Kim
This patch adds new PSTORE_FLAGS for each pstore type so that they can be enabled separately. This is a preparation for ongoing virtio-pstore work to support those types flexibly. The PSTORE_FLAGS_FRAGILE is changed to PSTORE_FLAGS_DMESG to preserve the original behavior. Cc: Anton Vorontsov <anton@enomsg.org> Cc: Colin Cross <ccross@android.com> Cc: Kees Cook <keescook@chromium.org> Cc: Tony Luck <tony.luck@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Len Brown <lenb@kernel.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: linux-acpi@vger.kernel.org Cc: linux-efi@vger.kernel.org Signed-off-by: Namhyung Kim <namhyung@kernel.org> [kees: retained "FRAGILE" for now to make merges easier] Signed-off-by: Kees Cook <keescook@chromium.org>
2016-06-02pstore: add lzo/lz4 compression supportGeliang Tang
Like zlib compression in pstore, this patch added lzo and lz4 compression support so that users can have more options and better compression ratio. The original code treats the compressed data together with the uncompressed ECC correction notice by using zlib decompress. The ECC correction notice is missing in the decompression process. The treatment also makes lzo and lz4 not working. So I treat them separately by using pstore_decompress() to treat the compressed data, and memcpy() to treat the uncompressed ECC correction notice. Signed-off-by: Geliang Tang <geliangtang@163.com> Signed-off-by: Kees Cook <keescook@chromium.org>
2015-10-22pstore: add pstore unregisterGeliang Tang
pstore doesn't support unregistering yet. It was marked as TODO. This patch adds some code to fix it: 1) Add functions to unregister kmsg/console/ftrace/pmsg. 2) Add a function to free compression buffer. 3) Unmap the memory and free it. 4) Add a function to unregister pstore filesystem. Signed-off-by: Geliang Tang <geliangtang@163.com> Acked-by: Kees Cook <keescook@chromium.org> [Removed __exit annotation from ramoops_remove(). Reported by Arnd Bergmann] Signed-off-by: Tony Luck <tony.luck@intel.com>
2015-03-23pstore: Add pstore type id for PPC64 opal nvram partitionHari Bathini
This patch adds a new PPC64 partition type to be used for opal specific nvram partition. A new partition type is needed as none of the existing type matches this partition type. Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2015-01-16pstore: Add pmsg - user-space accessible pstore objectMark Salyzyn
A secured user-space accessible pstore object. Writes to /dev/pmsg0 are appended to the buffer, on reboot the persistent contents are available in /sys/fs/pstore/pmsg-ramoops-[ID]. One possible use is syslogd, or other daemon, can write messages, then on reboot provides a means to triage user-space activities leading up to a panic as a companion to the pstore dmesg or console logs. Signed-off-by: Mark Salyzyn <salyzyn@android.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
2013-12-20pstore: Don't allow high traffic options on fragile devicesLuck, Tony
Some pstore backing devices use on board flash as persistent storage. These have limited numbers of write cycles so it is a poor idea to use them from high frequency operations. Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-08-19pstore: Introduce new argument 'compressed' in the read callbackAruna Balakrishnaiah
Backends will set the flag 'compressed' after reading the log from persistent store to indicate the data being returned to pstore is compressed or not. Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
2013-08-19pstore: Add new argument 'compressed' in pstore write callbackAruna Balakrishnaiah
Addition of new argument 'compressed' in the write call back will help the backend to know if the data passed from pstore is compressed or not (In case where compression fails.). If compressed, the backend can add a tag indicating the data is compressed while writing to persistent store. Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
2013-07-01pstore: Pass header size in the pstore write callbackAruna Balakrishnaiah
Header size is needed to distinguish between header and the dump data. Incorporate the addition of new argument (hsize) in the pstore write callback. Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-06-20powerpc/pseries: Read common partition via pstoreAruna Balakrishnaiah
This patch exploits pstore subsystem to read details of common partition in NVRAM to a separate file in /dev/pstore. For instance, common partition details will be stored in a file named [common-nvram-6]. Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com> Reviewed-by: Jim Keniston <jkenisto@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-06-20powerpc/pseries: Read of-config partition via pstoreAruna Balakrishnaiah
This patch set exploits the pstore subsystem to read details of of-config partition in NVRAM to a separate file in /dev/pstore. For instance, of-config partition details will be stored in a file named [of-nvram-5]. Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com> Reviewed-by: Jim Keniston <jkenisto@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-06-20powerpc/pseries: Read rtas partition via pstoreAruna Balakrishnaiah
This patch set exploits the pstore subsystem to read details of rtas partition in NVRAM to a separate file in /dev/pstore. For instance, rtas details will be stored in a file named [rtas-nvram-4]. Signed-off-by: Aruna Balakrishnaiah <aruna@linux.vnet.ibm.com> Reviewed-by: Jim Keniston <jkenisto@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-01-11pstore: Avoid deadlock in panic and emergency-restart pathSeiji Aguchi
[Issue] When pstore is in panic and emergency-restart paths, it may be blocked in those paths because it simply takes spin_lock. This is an example scenario which pstore may hang up in a panic path: - cpuA grabs psinfo->buf_lock - cpuB panics and calls smp_send_stop - smp_send_stop sends IRQ to cpuA - after 1 second, cpuB gives up on cpuA and sends an NMI instead - cpuA is now in an NMI handler while still holding buf_lock - cpuB is deadlocked This case may happen if a firmware has a bug and cpuA is stuck talking with it more than one second. Also, this is a similar scenario in an emergency-restart path: - cpuA grabs psinfo->buf_lock and stucks in a firmware - cpuB kicks emergency-restart via either sysrq-b or hangcheck timer. And then, cpuB is deadlocked by taking psinfo->buf_lock again. [Solution] This patch avoids the deadlocking issues in both panic and emergency_restart paths by introducing a function, is_non_blocking_path(), to check if a cpu can be blocked in current path. With this patch, pstore is not blocked even if another cpu has taken a spin_lock, in those paths by changing from spin_lock_irqsave to spin_trylock_irqsave. In addition, according to a comment of emergency_restart() in kernel/sys.c, spin_lock shouldn't be taken in an emergency_restart path to avoid deadlock. This patch fits the comment below. <snip> /** * emergency_restart - reboot the system * * Without shutting down any hardware or taking any locks * reboot the system. This is called when we know we are in * trouble so this is our best effort to reboot. This is * safe to call in interrupt context. */ void emergency_restart(void) <snip> Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com> Acked-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2012-11-26efi_pstore: Add a sequence counter to a variable nameSeiji Aguchi
[Issue] Currently, a variable name, which identifies each entry, consists of type, id and ctime. But if multiple events happens in a short time, a second/third event may fail to log because efi_pstore can't distinguish each event with current variable name. [Solution] A reasonable way to identify all events precisely is introducing a sequence counter to the variable name. The sequence counter has already supported in a pstore layer with "oopscount". So, this patch adds it to a variable name. Also, it is passed to read/erase callbacks of platform drivers in accordance with the modification of the variable name. <before applying this patch> a variable name of first event: dump-type0-1-12345678 a variable name of second event: dump-type0-1-12345678 type:0 id:1 ctime:12345678 If multiple events happen in a short time, efi_pstore can't distinguish them because variable names are same among them. <after applying this patch> it can be distinguishable by adding a sequence counter as follows. a variable name of first event: dump-type0-1-1-12345678 a variable name of Second event: dump-type0-1-2-12345678 type:0 id:1 sequence counter: 1(first event), 2(second event) ctime:12345678 In case of a write callback executed in pstore_console_write(), "0" is added to an argument of the write callback because it just logs all kernel messages and doesn't need to care about multiple events. Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Mike Waychison <mikew@google.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2012-11-26efi_pstore: Add ctime to argument of erase callbackSeiji Aguchi
[Issue] Currently, a variable name, which is used to identify each log entry, consists of type, id and ctime. But an erase callback does not use ctime. If efi_pstore supported just one log, type and id were enough. However, in case of supporting multiple logs, it doesn't work because it can't distinguish each entry without ctime at erasing time. <Example> As you can see below, efi_pstore can't differentiate first event from second one without ctime. a variable name of first event: dump-type0-1-12345678 a variable name of second event: dump-type0-1-23456789 type:0 id:1 ctime:12345678, 23456789 [Solution] This patch adds ctime to an argument of an erase callback. It works across reboots because ctime of pstore means the date that the record was originally stored. To do this, efi_pstore saves the ctime to variable name at writing time and passes it to pstore at reading time. Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com> Acked-by: Mike Waychison <mikew@google.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2012-09-06pstore/ftrace: Convert to its own enable/disable debugfs knobAnton Vorontsov
With this patch we no longer reuse function tracer infrastructure, now we register our own tracer back-end via a debugfs knob. It's a bit more code, but that is the only downside. On the bright side we have: - Ability to make persistent_ram module removable (when needed, we can move ftrace_ops struct into a module). Note that persistent_ram is still not removable for other reasons, but with this patch it's just one thing less to worry about; - Pstore part is more isolated from the generic function tracer. We tried it already by registering our own tracer in available_tracers, but that way we're loosing ability to see the traces while we record them to pstore. This solution is somewhere in the middle: we only register "internal ftracer" back-end, but not the "front-end"; - When there is only pstore tracing enabled, the kernel will only write to the pstore buffer, omitting function tracer buffer (which, of course, still can be enabled via 'echo function > current_tracer'). Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
2012-07-17pstore: Headers should include all stuff they useAnton Vorontsov
Headers should really include all the needed prototypes, types, defines etc. to be self-contained. This is a long-standing issue, but apparently the new tracing code unearthed it (SMP=n is also a prerequisite): In file included from fs/pstore/internal.h:4:0, from fs/pstore/ftrace.c:21: include/linux/pstore.h:43:15: error: field ‘read_mutex’ has incomplete type While at it, I also added the following: linux/types.h -> size_t, phys_addr_t, uXX and friends linux/spinlock.h -> spinlock_t linux/errno.h -> Exxxx linux/time.h -> struct timespec (struct passed by value) struct module and rs_control forward declaration (passed via pointers). Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-17pstore: Add persistent function tracingAnton Vorontsov
With this support kernel can save function call chain log into a persistent ram buffer that can be decoded and dumped after reboot through pstore filesystem. It can be used to determine what function was last called before a reset or panic. We store the log in a binary format and then decode it at read time. p.s. Mostly the code comes from trace_persistent.c driver found in the Android git tree, written by Colin Cross <ccross@android.com> (according to sign-off history). I reworked the driver a little bit, and ported it to pstore. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-07-17pstore: Introduce write_buf backend callbackAnton Vorontsov
For function tracing we need to stop using pstore.buf directly, since in a tracing callback we can't use spinlocks, and thus we can't safely use the global buffer. With write_buf callback, backends no longer need to access pstore.buf directly, and thus we can pass any buffers (e.g. allocated on stack). Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-06-13pstore: Add console log messages supportAnton Vorontsov
Pstore doesn't support logging kernel messages in run-time, it only dumps dmesg when kernel oopses/panics. This makes pstore useless for debugging hangs caused by HW issues or improper use of HW (e.g. weird device inserted -> driver tried to write a reserved bits -> SoC hanged. In that case we don't get any messages in the pstore. Therefore, let's add a runtime logging support: PSTORE_TYPE_CONSOLE. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Colin Cross <ccross@android.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2011-11-17pstore: pass reason to backend write callbackKees Cook
This allows a backend to filter on the dmesg reason as well as the pstore reason. When ramoops is switched to pstore, this is needed since it has no interest in storing non-crash dmesg details. Drop pstore_write() as it has no users, and handling the "reason" here has no obviously correct value. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-11-17pstore: pass allocated memory region back to callerKees Cook
The buf_lock cannot be held while populating the inodes, so make the backend pass forward an allocated and filled buffer instead. This solves the following backtrace. The effect is that "buf" is only ever used to notify the backends that something was written to it, and shouldn't be used in the read path. To replace the buf_lock during the read path, isolate the open/read/close loop with a separate mutex to maintain serialized access to the backend. Note that is is up to the pstore backend to cope if the (*write)() path is called in the middle of the read path. [ 59.691019] BUG: sleeping function called from invalid context at .../mm/slub.c:847 [ 59.691019] in_atomic(): 0, irqs_disabled(): 1, pid: 1819, name: mount [ 59.691019] Pid: 1819, comm: mount Not tainted 3.0.8 #1 [ 59.691019] Call Trace: [ 59.691019] [<810252d5>] __might_sleep+0xc3/0xca [ 59.691019] [<810a26e6>] kmem_cache_alloc+0x32/0xf3 [ 59.691019] [<810b53ac>] ? __d_lookup_rcu+0x6f/0xf4 [ 59.691019] [<810b68b1>] alloc_inode+0x2a/0x64 [ 59.691019] [<810b6903>] new_inode+0x18/0x43 [ 59.691019] [<81142447>] pstore_get_inode.isra.1+0x11/0x98 [ 59.691019] [<81142623>] pstore_mkfile+0xae/0x26f [ 59.691019] [<810a2a66>] ? kmem_cache_free+0x19/0xb1 [ 59.691019] [<8116c821>] ? ida_get_new_above+0x140/0x158 [ 59.691019] [<811708ea>] ? __init_rwsem+0x1e/0x2c [ 59.691019] [<810b67e8>] ? inode_init_always+0x111/0x1b0 [ 59.691019] [<8102127e>] ? should_resched+0xd/0x27 [ 59.691019] [<8137977f>] ? _cond_resched+0xd/0x21 [ 59.691019] [<81142abf>] pstore_get_records+0x52/0xa7 [ 59.691019] [<8114254b>] pstore_fill_super+0x7d/0x91 [ 59.691019] [<810a7ff5>] mount_single+0x46/0x82 [ 59.691019] [<8114231a>] pstore_mount+0x15/0x17 [ 59.691019] [<811424ce>] ? pstore_get_inode.isra.1+0x98/0x98 [ 59.691019] [<810a8199>] mount_fs+0x5a/0x12d [ 59.691019] [<810b9174>] ? alloc_vfsmnt+0xa4/0x14a [ 59.691019] [<810b9474>] vfs_kern_mount+0x4f/0x7d [ 59.691019] [<810b9d7e>] do_kern_mount+0x34/0xb2 [ 59.691019] [<810bb15f>] do_mount+0x5fc/0x64a [ 59.691019] [<810912fb>] ? strndup_user+0x2e/0x3f [ 59.691019] [<810bb3cb>] sys_mount+0x66/0x99 [ 59.691019] [<8137b537>] sysenter_do_call+0x12/0x26 Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-10-12pstore: make pstore write function return normal success/fail valueChen Gong
Currently pstore write interface employs record id as return value, but it is not enough because it can't tell caller if the write operation is successful. Pass the record id back via an argument pointer and return zero for success, non-zero for failure. Signed-off-by: Chen Gong <gong.chen@linux.intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-08-16pstore: change mutex locking to spin_locksDon Zickus
pstore was using mutex locking to protect read/write access to the backend plug-ins. This causes problems when pstore is executed in an NMI context through panic() -> kmsg_dump(). This patch changes the mutex to a spin_lock_irqsave then also checks to see if we are in an NMI context. If we are in an NMI and can't get the lock, just print a message stating that and blow by the locking. All this is probably a hack around the bigger locking problem but it solves my current situation of trying to sleep in an NMI context. Tested by loading the lkdtm module and executing a HARDLOCKUP which will cause the machine to panic inside the nmi handler. Signed-off-by: Don Zickus <dzickus@redhat.com> Acked-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22pstore: Make "part" unsignedMatthew Garrett
We'll never have a negative part, so just make this an unsigned int. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22pstore: Add extra context for writes and erasesMatthew Garrett
EFI only provides small amounts of individual storage, and conventionally puts metadata in the storage variable name. Rather than add a metadata header to the (already limited) variable storage, it's easier for us to modify pstore to pass all the information we need to construct a unique variable name to the appropriate functions. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22pstore: Extend API for more flexibility in new backendsMatthew Garrett
Some pstore implementations may not have a static context, so extend the API to pass the pstore_info struct to all calls and allow for a context pointer. Signed-off-by: Matthew Garrett <mjg@redhat.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-05-16pstore: fix pstore filesystem mount/remount issueChen Gong
Currently after mount/remount operation on pstore filesystem, the content on pstore will be lost. It is because current ERST implementation doesn't support multi-user usage, which moves internal pointer to the end after accessing it. Adding multi-user support for pstore usage. Signed-off-by: Chen Gong <gong.chen@linux.intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-05-16pstore: fix one type of return value in pstoreChen Gong
the return type of function _read_ in pstore is size_t, but in the callback function of _read_, the logic doesn't consider it too much, which means if negative value (assuming error here) is returned, it will be converted to positive because of type casting. ssize_t is enough for this function. Signed-off-by: Chen Gong <gong.chen@linux.intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
2010-12-28pstore: new filesystem interface to platform persistent storageTony Luck
Some platforms have a small amount of non-volatile storage that can be used to store information useful to diagnose the cause of a system crash. This is the generic part of a file system interface that presents information from the crash as a series of files in /dev/pstore. Once the information has been seen, the underlying storage is freed by deleting the files. Signed-off-by: Tony Luck <tony.luck@intel.com>