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We really need to use a ACCESS_ONCE() on the sequence value read in
__read_seqcount_begin(), because otherwise the compiler might end up
reloading the value in between the test and the return of it. As a
result, it might end up returning an odd value (which means that a write
is in progress).
If the reader is then fast enough that that odd value is still the
current one when the read_seqcount_retry() is done, we might end up with
a "successful" read sequence, even despite the concurrent write being
active.
In practice this probably never really happens - there just isn't
anything else going on around the read of the sequence count, and the
common case is that we end up having a read barrier immediately
afterwards.
So the code sequence in which gcc might decide to reaload from memory is
small, and there's no reason to believe it would ever actually do the
reload. But if the compiler ever were to decide to do so, it would be
incredibly annoying to debug. Let's just make sure.
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It appears some networks play bad games with the two bits reserved for
ECN. This can trigger false congestion notifications and very slow
transferts.
Since RFC 3168 (6.1.1) forbids SYN packets to carry CT bits, we can
disable TCP ECN negociation if it happens we receive mangled CT bits in
the SYN packet.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Perry Lorier <perryl@google.com>
Cc: Matt Mathis <mattmathis@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Wilmer van der Gaast <wilmer@google.com>
Cc: Ankur Jain <jankur@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Dave Täht <dave.taht@bufferbloat.net>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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With multiple cards is hard to figure out which port caused trouble
int the layer2 routines (e.g. got a timeout).
Now we have the informations in the log output.
Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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For certification test it is very useful to change the layer1
timer3 value on runtime.
Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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To be full preemptiv safe, we cannot handle a L2 timeout in the timer
context itself, we should do all actions via the D-channel thread.
Signed-off-by: Karsten Keil <kkeil@linux-pingi.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This commit adds device tree support for the TPS6586x regulator.
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
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Looking up init data for regulators found on chips is a common operation
that can be handled in a generic way. The new helper function introduced
by this patch looks up the children of a given node by names specified
in a match table and fills that match table with information parsed from
the DT.
This is based on work by Rhyland Klein <rklein@nvidia.com>.
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
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Linux 3.4-rc5
Merge to pull in prerequisite change for Smack:
86812bb0de1a3758dc6c7aa01a763158a7c0638a
Requested by Casey.
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Pull networking fixes from David Miller:
1) Transfer padding was wrong for full-speed USB in ASIX driver, fix
from Ingo van Lil.
2) Propagate the negative packet offset fix into the PowerPC BPF JIT.
From Jan Seiffert.
3) dl2k driver's private ioctls were letting unprivileged tasks make
MII writes and other ugly bits like that. Fix from Jeff Mahoney.
4) Fix TX VLAN and RX packet drops in ucc_geth, from Joakim Tjernlund.
5) OOPS and network namespace fixes in IPVS from Hans Schillstrom and
Julian Anastasov.
6) Fix races and sleeping in locked context bugs in drop_monitor, from
Neil Horman.
7) Fix link status indication in smsc95xx driver, from Paolo Pisati.
8) Fix bridge netfilter OOPS, from Peter Huang.
9) L2TP sendmsg can return on error conditions with the socket lock
held, oops. Fix from Sasha Levin.
10) udp_diag should return meaningful values for socket memory usage,
from Shan Wei.
11) Eric Dumazet is so awesome he gets his own section:
Socket memory cgroup code (I never should have applied those
patches, grumble...) made erroneous changes to
sk_sockets_allocated_read_positive(). It was changed to
use percpu_counter_sum_positive (which requires BH disabling)
instead of percpu_counter_read_positive (which does not).
Revert back to avoid crashes and lockdep warnings.
Adjust the default tcp_adv_win_scale and tcp_rmem[2] values
to fix throughput regressions. This is necessary as a result
of our more precise skb->truesize tracking.
Fix SKB leak in netem packet scheduler.
12) New device IDs for various bluetooth devices, from Manoj Iyer,
AceLan Kao, and Steven Harms.
13) Fix command completion race in ipw2200, from Stanislav Yakovlev.
14) Fix rtlwifi oops on unload, from Larry Finger.
15) Fix hard_mtu when adjusting hard_header_len in smsc95xx driver.
From Stephane Fillod.
16) ehea driver registers it's IRQ before all the necessary state is
setup, resulting in crashes. Fix from Thadeu Lima de Souza
Cascardo.
17) Fix PHY connection failures in davinci_emac driver, from Anatolij
Gustschin.
18) Missing break; in switch statement in bluetooth's
hci_cmd_complete_evt(). Fix from Szymon Janc.
19) Fix queue programming in iwlwifi, from Johannes Berg.
20) Interrupt throttling defaults not being actually programmed into the
hardware, fix from Jeff Kirsher and Ying Cai.
21) TLAN driver SKB encoding in descriptor busted on 64-bit, fix from
Benjamin Poirier.
22) Fix blind status block RX producer pointer deref in TG3 driver, from
Matt Carlson.
23) Promisc and multicast are busted on ehea, fixes from Thadeu Lima de
Souza Cascardo.
24) Fix crashes in 6lowpan, from Alexander Smirnov.
25) tcp_complete_cwr() needs to be careful to not rewind the CWND to
ssthresh if ssthresh has the "infinite" value. Fix from Yuchung
Cheng.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (81 commits)
sungem: Fix WakeOnLan
tcp: change tcp_adv_win_scale and tcp_rmem[2]
net: l2tp: unlock socket lock before returning from l2tp_ip_sendmsg
drop_monitor: prevent init path from scheduling on the wrong cpu
usbnet: fix failure handling in usbnet_probe
usbnet: fix leak of transfer buffer of dev->interrupt
ucc_geth: Add 16 bytes to max TX frame for VLANs
net: ucc_geth, increase no. of HW RX descriptors
netem: fix possible skb leak
sky2: fix receive length error in mixed non-VLAN/VLAN traffic
sky2: propogate rx hash when packet is copied
net: fix two typos in skbuff.h
cxgb3: Don't call cxgb_vlan_mode until q locks are initialized
ixgbe: fix calling skb_put on nonlinear skb assertion bug
ixgbe: Fix a memory leak in IEEE DCB
igbvf: fix the bug when initializing the igbvf
smsc75xx: enable mac to detect speed/duplex from phy
smsc75xx: declare smsc75xx's MII as GMII capable
smsc75xx: fix phy interrupt acknowledge
smsc75xx: fix phy init reset loop
...
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This patch adds support for a skb_head_is_locked helper function. It is
meant to be used any time we are considering transferring the head from
skb->head to a paged frag. If the head is locked it means we cannot remove
the head from the skb so it must be copied or we must take the skb as a
whole.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Extend tcp coalescing implementing it from tcp_queue_rcv(), the main
receiver function when application is not blocked in recvmsg().
Function tcp_queue_rcv() is moved a bit to allow its call from
tcp_data_queue()
This gives good results especially if GRO could not kick, and if skb
head is a fragment.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Implementing the advanced early retransmit (sysctl_tcp_early_retrans==2).
Delays the fast retransmit by an interval of RTT/4. We borrow the
RTO timer to implement the delay. If we receive another ACK or send
a new packet, the timer is cancelled and restored to original RTO
value offset by time elapsed. When the delayed-ER timer fires,
we enter fast recovery and perform fast retransmit.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch implements RFC 5827 early retransmit (ER) for TCP.
It reduces DUPACK threshold (dupthresh) if outstanding packets are
less than 4 to recover losses by fast recovery instead of timeout.
While the algorithm is simple, small but frequent network reordering
makes this feature dangerous: the connection repeatedly enter
false recovery and degrade performance. Therefore we implement
a mitigation suggested in the appendix of the RFC that delays
entering fast recovery by a small interval, i.e., RTT/4. Currently
ER is conservative and is disabled for the rest of the connection
after the first reordering event. A large scale web server
experiment on the performance impact of ER is summarized in
section 6 of the paper "Proportional Rate Reduction for TCP”,
IMC 2011. http://conferences.sigcomm.org/imc/2011/docs/p155.pdf
Note that Linux has a similar feature called THIN_DUPACK. The
differences are THIN_DUPACK do not mitigate reorderings and is only
used after slow start. Currently ER is disabled if THIN_DUPACK is
enabled. I would be happy to merge THIN_DUPACK feature with ER if
people think it's a good idea.
ER is enabled by sysctl_tcp_early_retrans:
0: Disables ER
1: Reduce dupthresh to packets_out - 1 when outstanding packets < 4.
2: (Default) reduce dupthresh like mode 1. In addition, delay
entering fast recovery by RTT/4.
Note: mode 2 is implemented in the third part of this patch series.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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When running preemptible RCU, if a task exits in an RCU read-side
critical section having blocked within that same RCU read-side critical
section, the task must be removed from the list of tasks blocking a
grace period (perhaps the current grace period, perhaps the next grace
period, depending on timing). The exit() path invokes exit_rcu() to
do this cleanup.
However, the current implementation of exit_rcu() needlessly does the
cleanup even if the task did not block within the current RCU read-side
critical section, which wastes time and needlessly increases the size
of the state space. Fix this by only doing the cleanup if the current
task is actually on the list of tasks blocking some grace period.
While we are at it, consolidate the two identical exit_rcu() functions
into a single function.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
Conflicts:
kernel/rcupdate.c
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Currently, PREEMPT_RCU readers are enqueued upon entry to the scheduler.
This is inefficient because enqueuing is required only if there is a
context switch, and entry to the scheduler does not guarantee a context
switch.
The commit therefore moves the enqueuing to immediately precede the
call to switch_to() from the scheduler.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
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The common clock framework allocates clocks dynamically. Provide a
set of helpers to streamline the clkdev registration of the clock
lookups to avoid repetitive code sequences.
Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Currently most code to get child count in kernel are almost same,
add a helper to implement this function for dt to use.
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless into for-davem
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fix kernel doc typos in function names
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add ECN (Explicit Congestion Notification) marking capability to netem
tc qdisc add dev eth0 root netem drop 0.5 ecn
Instead of dropping packets, try to ECN mark them.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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remove useless casts and rename variables for less confusion.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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L2TPv3 defines an IP encapsulation packet format where data is carried
directly over IP (no UDP). The kernel already has support for L2TP IP
encapsulation over IPv4 (l2tp_ip). This patch introduces support for
L2TP IP encapsulation over IPv6.
The implementation is derived from ipv6/raw and ipv4/l2tp_ip.
Signed-off-by: Chris Elston <celston@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch adds support for unmanaged L2TPv3 tunnels over IPv6 using
the netlink API. We already support unmanaged L2TPv3 tunnels over
IPv4. A patch to iproute2 to make use of this feature will be
submitted separately.
Signed-off-by: Chris Elston <celston@katalix.com>
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Checkpatch warns about the use of __attribute__((packed)). So use the
recommended __packed syntax instead.
Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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GRO can check if skb to be merged has its skb->head mapped to a page
fragment, instead of a kmalloc() area.
We 'upgrade' skb->head as a fragment in itself
This avoids the frag_list fallback, and permits to build true GRO skb
(one sk_buff and up to 16 fragments), using less memory.
This reduces number of cache misses when user makes its copy, since a
single sk_buff is fetched.
This is a followup of patch "net: allow skb->head to be a page fragment"
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Matt Carlson <mcarlson@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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skb->head is currently allocated from kmalloc(). This is convenient but
has the drawback the data cannot be converted to a page fragment if
needed.
We have three spots were it hurts :
1) GRO aggregation
When a linear skb must be appended to another skb, GRO uses the
frag_list fallback, very inefficient since we keep all struct sk_buff
around. So drivers enabling GRO but delivering linear skbs to network
stack aren't enabling full GRO power.
2) splice(socket -> pipe).
We must copy the linear part to a page fragment.
This kind of defeats splice() purpose (zero copy claim)
3) TCP coalescing.
Recently introduced, this permits to group several contiguous segments
into a single skb. This shortens queue lengths and save kernel memory,
and greatly reduce probabilities of TCP collapses. This coalescing
doesnt work on linear skbs (or we would need to copy data, this would be
too slow)
Given all these issues, the following patch introduces the possibility
of having skb->head be a fragment in itself. We use a new skb flag,
skb->head_frag to carry this information.
build_skb() is changed to accept a frag_size argument. Drivers willing
to provide a page fragment instead of kmalloc() data will set a non zero
value, set to the fragment size.
Then, on situations we need to convert the skb head to a frag in itself,
we can check if skb->head_frag is set and avoid the copies or various
fallbacks we have.
This means drivers currently using frags could be updated to avoid the
current skb->head allocation and reduce their memory footprint (aka skb
truesize). (thats 512 or 1024 bytes saved per skb). This also makes
bpf/netfilter faster since the 'first frag' will be part of skb linear
part, no need to copy data.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Matt Carlson <mcarlson@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI fixes from James Bottomley:
"This is a set of SAS and SATA fixes; there are one or two longstanding
bug fixes, but most of this is regression fixes."
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
[SCSI] libfc: update mfs boundry checking
[SCSI] Revert "[SCSI] libsas: fix sas port naming"
[SCSI] libsas: fix false positive 'device attached' conditions
[SCSI] libsas, libata: fix start of life for a sas ata_port
[SCSI] libsas: fix ata_eh clobbering ex_phys via smp_ata_check_ready
[SCSI] libsas: unify domain_device sas_rphy lifetimes
[SCSI] libsas: fix sas_get_port_device regression
[SCSI] libsas: fix sas_find_bcast_phy() in the presence of 'vacant' phys
[SCSI] libsas: introduce sas_work to fix sas_drain_work vs sas_queue_work
[SCSI] libata: Pass correct DMA device to scsi host
[SCSI] scsi_lib: use correct DMA device in __scsi_alloc_queue
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More recent versions of the UEFI spec have added new attributes for
variables. Add them.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Some devices does not support bulk read and write operations, for them
we have series of single write and read operations.
Signed-off-by: Anthony Olech <Anthony.Olech@diasemi.com>
Signed-off-by: Ashish Jangam <ashish.jangam@kpitcummins.com>
[Fixed coding style, don't check use_single_rw before assign --broonie ]
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
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A PCIe downstream port is a P2P bridge. Its secondary interface is
a link that should lead only to device 0 (unless ARI is enabled)[1], so
we don't probe for non-zero device numbers.
Some Stratus ftServer systems have a PCIe downstream port (02:00.0) that
leads to both an upstream port (03:00.0) and a downstream port (03:01.0),
and 03:01.0 has important devices below it:
[0000:02]-+-00.0-[03-3c]--+-00.0-[04-09]--...
\-01.0-[0a-0d]--+-[USB]
+-[NIC]
+-...
Previously, we didn't enumerate device 03:01.0, so USB and the network
didn't work. This patch adds a DMI quirk to scan all device numbers,
not just 0, below a downstream port.
Based on a patch by Prarit Bhargava.
[1] PCIe spec r3.0, sec 7.3.1
CC: Myron Stowe <mstowe@redhat.com>
CC: Don Dutile <ddutile@redhat.com>
CC: James Paradis <james.paradis@stratus.com>
CC: Matthew Wilcox <matthew.r.wilcox@intel.com>
CC: Jesse Barnes <jbarnes@virtuousgeek.org>
CC: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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We need a hook to release host bridge resources allocated when creating
root bus.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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<asm-generic/statfs.h> is exported to userspace, so using
BITS_PER_LONG is invalid. We need to use __BITS_PER_LONG instead.
This is kernel bugzilla 43165.
Reported-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1335465916-16965-1-git-send-email-hpa@linux.intel.com
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: <stable@vger.kernel.org>
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Use that device for pci_root_bus bridge pointer.
Use pci_release_bus_bridge_dev() to release allocated pci_host_bridge in
remove path.
Use root bus bridge pointer to get host bridge pointer instead of searching
host bridge list. That leaves the host bridge list unused, so remove it.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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This commit implements an SRCU state machine in support of call_srcu().
The state machine is preemptible, light-weight, and single-threaded,
minimizing synchronization overhead. In particular, there is no longer
any need for synchronize_srcu() to be guarded by a mutex.
Expedited processing is handled, at least in the absence of concurrent
grace-period operations on that same srcu_struct structure, by having
the synchronize_srcu_expedited() thread take on the role of the
workqueue thread for one iteration.
There is a reasonable probability that a given SRCU callback will
be invoked on the same CPU that registered it, however, there is no
guarantee. Concurrent SRCU grace-period primitives can cause callbacks
to be executed elsewhere, even in absence of CPU-hotplug operations.
Callbacks execute in process context, but under the influence of
local_bh_disable(), so it is illegal to sleep in an SRCU callback
function.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The old srcu_barrier() macro is now unused. This commit removes it so
that it may be used for the SRCU flavor of rcu_barrier(), which will in
turn be needed to allow the upcoming call_srcu() to be used from within
modules.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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This commit implements a variant of Peter's algorithm, which may be found
at https://lkml.org/lkml/2012/2/1/119.
o Make the checking lock-free to enable parallel checking.
Parallel checking is required when (1) the original checking
task is preempted for a long time, (2) sychronize_srcu_expedited()
starts during an ongoing SRCU grace period, or (3) we wish to
avoid acquiring a lock.
o Since the checking is lock-free, we avoid a mutex in state machine
for call_srcu().
o Remove the SRCU_REF_MASK and remove the coupling with the flipping.
This might allow us to remove the preempt_disable() in future
versions, though such removal will need great care because it
rescinds the one-old-reader-per-CPU guarantee.
o Remove a smp_mb(), simplify the comments and make the smp_mb() pairs
more intuitive.
Inspired-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The purpose of the upper bit of SRCU's per-CPU counters is to guarantee
that no reasonable series of srcu_read_lock() and srcu_read_unlock()
operations can return the value of the counter to its original value.
This guarantee is require only after the index has been switched to
the other set of counters, so at most one srcu_read_lock() can affect
a given CPU's counter. The number of srcu_read_unlock() operations
on a given counter is limited to the number of tasks in the system,
which given the Linux kernel's current structure is limited to far less
than 2^30 on 32-bit systems and far less than 2^62 on 64-bit systems.
(Something about a limited number of bytes in the kernel's address space.)
Therefore, if srcu_read_lock() increments the upper bits, then
srcu_read_unlock() need not do so. In this case, an srcu_read_lock() and
an srcu_read_unlock() will flip the lower bit of the upper field of the
counter. An unreasonably large additional number of srcu_read_unlock()
operations would be required to return the counter to its initial value,
thus preserving the guarantee.
This commit takes this approach, which further allows it to shrink
the size of the upper field to one bit, making the number of
srcu_read_unlock() operations required to return the counter to its
initial value even more unreasonable than before.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The current implementation of synchronize_srcu_expedited() can cause
severe OS jitter due to its use of synchronize_sched(), which in turn
invokes try_stop_cpus(), which causes each CPU to be sent an IPI.
This can result in severe performance degradation for real-time workloads
and especially for short-interation-length HPC workloads. Furthermore,
because only one instance of try_stop_cpus() can be making forward progress
at a given time, only one instance of synchronize_srcu_expedited() can
make forward progress at a time, even if they are all operating on
distinct srcu_struct structures.
This commit, inspired by an earlier implementation by Peter Zijlstra
(https://lkml.org/lkml/2012/1/31/211) and by further offline discussions,
takes a strictly algorithmic bits-in-memory approach. This has the
disadvantage of requiring one explicit memory-barrier instruction in
each of srcu_read_lock() and srcu_read_unlock(), but on the other hand
completely dispenses with OS jitter and furthermore allows SRCU to be
used freely by CPUs that RCU believes to be idle or offline.
The update-side implementation handles the single read-side memory
barrier by rechecking the per-CPU counters after summing them and
by running through the update-side state machine twice.
This implementation has passed moderate rcutorture testing on both
x86 and Power. Also updated to use this_cpu_ptr() instead of per_cpu_ptr(),
as suggested by Peter Zijlstra.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
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Denys Fedoryshchenko reported frequent crashes on a proxy server and kindly
provided a lockdep report that explains it all :
[ 762.903868]
[ 762.903880] =================================
[ 762.903890] [ INFO: inconsistent lock state ]
[ 762.903903] 3.3.4-build-0061 #8 Not tainted
[ 762.904133] ---------------------------------
[ 762.904344] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
[ 762.904542] squid/1603 [HC0[0]:SC0[0]:HE1:SE1] takes:
[ 762.904542] (key#3){+.?...}, at: [<c0232cc4>]
__percpu_counter_sum+0xd/0x58
[ 762.904542] {IN-SOFTIRQ-W} state was registered at:
[ 762.904542] [<c0158b84>] __lock_acquire+0x284/0xc26
[ 762.904542] [<c01598e8>] lock_acquire+0x71/0x85
[ 762.904542] [<c0349765>] _raw_spin_lock+0x33/0x40
[ 762.904542] [<c0232c93>] __percpu_counter_add+0x58/0x7c
[ 762.904542] [<c02cfde1>] sk_clone_lock+0x1e5/0x200
[ 762.904542] [<c0303ee4>] inet_csk_clone_lock+0xe/0x78
[ 762.904542] [<c0315778>] tcp_create_openreq_child+0x1b/0x404
[ 762.904542] [<c031339c>] tcp_v4_syn_recv_sock+0x32/0x1c1
[ 762.904542] [<c031615a>] tcp_check_req+0x1fd/0x2d7
[ 762.904542] [<c0313f77>] tcp_v4_do_rcv+0xab/0x194
[ 762.904542] [<c03153bb>] tcp_v4_rcv+0x3b3/0x5cc
[ 762.904542] [<c02fc0c4>] ip_local_deliver_finish+0x13a/0x1e9
[ 762.904542] [<c02fc539>] NF_HOOK.clone.11+0x46/0x4d
[ 762.904542] [<c02fc652>] ip_local_deliver+0x41/0x45
[ 762.904542] [<c02fc4d1>] ip_rcv_finish+0x31a/0x33c
[ 762.904542] [<c02fc539>] NF_HOOK.clone.11+0x46/0x4d
[ 762.904542] [<c02fc857>] ip_rcv+0x201/0x23e
[ 762.904542] [<c02daa3a>] __netif_receive_skb+0x319/0x368
[ 762.904542] [<c02dac07>] netif_receive_skb+0x4e/0x7d
[ 762.904542] [<c02dacf6>] napi_skb_finish+0x1e/0x34
[ 762.904542] [<c02db122>] napi_gro_receive+0x20/0x24
[ 762.904542] [<f85d1743>] e1000_receive_skb+0x3f/0x45 [e1000e]
[ 762.904542] [<f85d3464>] e1000_clean_rx_irq+0x1f9/0x284 [e1000e]
[ 762.904542] [<f85d3926>] e1000_clean+0x62/0x1f4 [e1000e]
[ 762.904542] [<c02db228>] net_rx_action+0x90/0x160
[ 762.904542] [<c012a445>] __do_softirq+0x7b/0x118
[ 762.904542] irq event stamp: 156915469
[ 762.904542] hardirqs last enabled at (156915469): [<c019b4f4>]
__slab_alloc.clone.58.clone.63+0xc4/0x2de
[ 762.904542] hardirqs last disabled at (156915468): [<c019b452>]
__slab_alloc.clone.58.clone.63+0x22/0x2de
[ 762.904542] softirqs last enabled at (156915466): [<c02ce677>]
lock_sock_nested+0x64/0x6c
[ 762.904542] softirqs last disabled at (156915464): [<c0349914>]
_raw_spin_lock_bh+0xe/0x45
[ 762.904542]
[ 762.904542] other info that might help us debug this:
[ 762.904542] Possible unsafe locking scenario:
[ 762.904542]
[ 762.904542] CPU0
[ 762.904542] ----
[ 762.904542] lock(key#3);
[ 762.904542] <Interrupt>
[ 762.904542] lock(key#3);
[ 762.904542]
[ 762.904542] *** DEADLOCK ***
[ 762.904542]
[ 762.904542] 1 lock held by squid/1603:
[ 762.904542] #0: (sk_lock-AF_INET){+.+.+.}, at: [<c03055c0>]
lock_sock+0xa/0xc
[ 762.904542]
[ 762.904542] stack backtrace:
[ 762.904542] Pid: 1603, comm: squid Not tainted 3.3.4-build-0061 #8
[ 762.904542] Call Trace:
[ 762.904542] [<c0347b73>] ? printk+0x18/0x1d
[ 762.904542] [<c015873a>] valid_state+0x1f6/0x201
[ 762.904542] [<c0158816>] mark_lock+0xd1/0x1bb
[ 762.904542] [<c015876b>] ? mark_lock+0x26/0x1bb
[ 762.904542] [<c015805d>] ? check_usage_forwards+0x77/0x77
[ 762.904542] [<c0158bf8>] __lock_acquire+0x2f8/0xc26
[ 762.904542] [<c0159b8e>] ? mark_held_locks+0x5d/0x7b
[ 762.904542] [<c0159cf6>] ? trace_hardirqs_on+0xb/0xd
[ 762.904542] [<c0158dd4>] ? __lock_acquire+0x4d4/0xc26
[ 762.904542] [<c01598e8>] lock_acquire+0x71/0x85
[ 762.904542] [<c0232cc4>] ? __percpu_counter_sum+0xd/0x58
[ 762.904542] [<c0349765>] _raw_spin_lock+0x33/0x40
[ 762.904542] [<c0232cc4>] ? __percpu_counter_sum+0xd/0x58
[ 762.904542] [<c0232cc4>] __percpu_counter_sum+0xd/0x58
[ 762.904542] [<c02cebc4>] __sk_mem_schedule+0xdd/0x1c7
[ 762.904542] [<c02d178d>] ? __alloc_skb+0x76/0x100
[ 762.904542] [<c0305e8e>] sk_wmem_schedule+0x21/0x2d
[ 762.904542] [<c0306370>] sk_stream_alloc_skb+0x42/0xaa
[ 762.904542] [<c0306567>] tcp_sendmsg+0x18f/0x68b
[ 762.904542] [<c031f3dc>] ? ip_fast_csum+0x30/0x30
[ 762.904542] [<c0320193>] inet_sendmsg+0x53/0x5a
[ 762.904542] [<c02cb633>] sock_aio_write+0xd2/0xda
[ 762.904542] [<c015876b>] ? mark_lock+0x26/0x1bb
[ 762.904542] [<c01a1017>] do_sync_write+0x9f/0xd9
[ 762.904542] [<c01a2111>] ? file_free_rcu+0x2f/0x2f
[ 762.904542] [<c01a17a1>] vfs_write+0x8f/0xab
[ 762.904542] [<c01a284d>] ? fget_light+0x75/0x7c
[ 762.904542] [<c01a1900>] sys_write+0x3d/0x5e
[ 762.904542] [<c0349ec9>] syscall_call+0x7/0xb
[ 762.904542] [<c0340000>] ? rp_sidt+0x41/0x83
Bug is that sk_sockets_allocated_read_positive() calls
percpu_counter_sum_positive() without BH being disabled.
This bug was added in commit 180d8cd942ce33
(foundations of per-cgroup memory pressure controlling.), since previous
code was using percpu_counter_read_positive() which is IRQ safe.
In __sk_mem_schedule() we dont need the precise count of allocated
sockets and can revert to previous behavior.
Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
Sined-off-by: Eric Dumazet <edumazet@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Change order of init so netns init is ready
when register ioctl and netlink.
Ver2
Whitespace fixes and __init added.
Reported-by: "Ryan O'Hara" <rohara@redhat.com>
Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
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ip_vs_create_timeout_table() can return NULL
All functions protocol init_netns is affected of this patch.
Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
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The actual internal pipe implementation is already really about
individual packets (called "pipe buffers"), and this simply exposes that
as a special packetized mode.
When we are in the packetized mode (marked by O_DIRECT as suggested by
Alan Cox), a write() on a pipe will not merge the new data with previous
writes, so each write will get a pipe buffer of its own. The pipe
buffer is then marked with the PIPE_BUF_FLAG_PACKET flag, which in turn
will tell the reader side to break the read at that boundary (and throw
away any partial packet contents that do not fit in the read buffer).
End result: as long as you do writes less than PIPE_BUF in size (so that
the pipe doesn't have to split them up), you can now treat the pipe as a
packet interface, where each read() system call will read one packet at
a time. You can just use a sufficiently big read buffer (PIPE_BUF is
sufficient, since bigger than that doesn't guarantee atomicity anyway),
and the return value of the read() will naturally give you the size of
the packet.
NOTE! We do not support zero-sized packets, and zero-sized reads and
writes to a pipe continue to be no-ops. Also note that big packets will
currently be split at write time, but that the size at which that
happens is not really specified (except that it's bigger than PIPE_BUF).
Currently that limit is the system page size, but we might want to
explicitly support bigger packets some day.
The main user for this is going to be the autofs packet interface,
allowing us to stop having to care so deeply about exact packet sizes
(which have had bugs with 32/64-bit compatibility modes). But user
space can create packetized pipes with "pipe2(fd, O_DIRECT)", which will
fail with an EINVAL on kernels that do not support this interface.
Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Miller <davem@davemloft.net>
Cc: Ian Kent <raven@themaw.net>
Cc: Thomas Meyer <thomas@m3y3r.de>
Cc: stable@kernel.org # needed for systemd/autofs interaction fix
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB fixes from Greg Kroah-Hartman:
"Here are a number of small USB fixes for 3.4-rc5.
Nothing major, as before, some USB gadget fixes. There's a crash fix
for a number of ASUS laptops on resume that had been reported by a
number of different people. We think the fix might also pertain to
other machines, as this was a BIOS bug, and they seem to travel to
different models and manufacturers quite easily. Other than that,
some other reported problems fixed as well."
* tag 'usb-3.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
usb: gadget: udc-core: fix incompatibility with dummy-hcd
usb: gadget: udc-core: fix wrong call order
USB: cdc-wdm: fix race leading leading to memory corruption
USB: EHCI: fix crash during suspend on ASUS computers
usb gadget: uvc: uvc_request_data::length field must be signed
usb: gadget: dummy: do not call pullup() on udc_stop()
usb: musb: davinci.c: add missing unregister
usb: musb: drop __deprecated flag
USB: gadget: storage gadgets send wrong error code for unknown commands
usb: otg: gpio_vbus: Add otg transceiver events and notifiers
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Now that encap_rcv() works on IPv6 UDP sockets, wire L2TP up to IPv6.
Support has been tested with and without hardware offloading. This
version fixes the L2TP over localhost issue with incorrect checksums
being reported.
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Now that the sematics of udpv6_queue_rcv_skb() match IPv4's
udp_queue_rcv_skb(), introduce the UDP encap_rcv() hook for IPv6.
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
Pull ARM SoC fixes from Olof Johansson:
"Nothing controversial, just another batch of fixes:
- Samsung/exynos fixes for more merge window fallout: build errors
and warnings mostly, but also some clock/device setup issues on
exynos4/5
- PXA bug and warning fixes related to gpio and pinmux
- IRQ domain conversion bugfixes for U300 and MSM
- A regulator setup fix for U300"
* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
ARM: PXA2xx: MFP: fix potential direction bug
ARM: PXA2xx: MFP: fix bug with MFP_LPM_KEEP_OUTPUT
arm/sa1100: fix sa1100-rtc memory resource
ARM: pxa: fix gpio wakeup setting
ARM: SAMSUNG: add missing MMC_CAP2_BROKEN_VOLTAGE capability
ARM: EXYNOS: Fix compilation error when CONFIG_OF is not defined
ARM: EXYNOS: Fix resource on dev-dwmci.c
ARM: S3C24XX: Fix build warning for S3C2410_PM
ARM: mini2440_defconfig: Fix build error
ARM: msm: Fix gic irqdomain support
ARM: EXYNOS: Fix incorrect initialization of GIC
ARM: EXYNOS: use 'exynos4-sdhci' as device name for sdhci controllers
ARM: u300: bump all IRQ numbers by one
ARM: ux300: Fix unimplementable regulation constraints
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Pull misc SPI device driver bug fixes from Grant Likely.
* tag 'spi-for-linus' of git://git.secretlab.ca/git/linux-2.6:
spi/spi-bfin5xx: Fix flush of last bit after each spi transfer
spi/spi-bfin5xx: fix reversed if condition in interrupt mode
spi/spi_bfin_sport: drop bits_per_word from client data
spi/bfin_spi: drop bits_per_word from client data
spi/spi-bfin-sport: move word length setup to transfer handler
spi/bfin5xx: rename config macro name for bfin5xx spi controller driver
spi/pl022: Allow request for higher frequency than maximum possible
spi/bcm63xx: set master driver mode_bits.
spi/bcm63xx: don't use the stopping state
spi/bcm63xx: convert to the pump message infrastructure
spi/spi-ep93xx.c: use dma_transfer_direction instead of dma_data_direction
spi: fix spi.h kernel-doc warning
spi/pl022: Fix calculate_effective_freq()
spi/pl022: Fix range checking for bits per word
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git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth
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Fix kernel-doc warning in spi.h (copy/paste):
Warning(include/linux/spi/spi.h:365): No description found for parameter 'unprepare_transfer_hardware'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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