mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 05:48:40 +00:00
![]() Write space becoming available may race with putting the task to sleep in xprt_wait_for_buffer_space(). The existing mechanism to avoid the race does not work. This (edited) partial trace illustrates the problem: [1] rpc_task_run_action: task:43546@5 ... action=call_transmit [2] xs_write_space <-xs_tcp_write_space [3] xprt_write_space <-xs_write_space [4] rpc_task_sleep: task:43546@5 ... [5] xs_write_space <-xs_tcp_write_space [1] Task 43546 runs but is out of write space. [2] Space becomes available, xs_write_space() clears the SOCKWQ_ASYNC_NOSPACE bit. [3] xprt_write_space() attemts to wake xprt->snd_task (== 43546), but this has not yet been queued and the wake up is lost. [4] xs_nospace() is called which calls xprt_wait_for_buffer_space() which queues task 43546. [5] The call to sk->sk_write_space() at the end of xs_nospace() (which is supposed to handle the above race) does not call xprt_write_space() as the SOCKWQ_ASYNC_NOSPACE bit is clear and thus the task is not woken. Fix the race by resetting the SOCKWQ_ASYNC_NOSPACE bit in xs_nospace() so the second call to sk->sk_write_space() calls xprt_write_space(). Suggested-by: Trond Myklebust <trondmy@primarydata.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com> cc: stable@vger.kernel.org # 4.4 Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> |
||
---|---|---|
.. | ||
auth_gss | ||
xprtrdma | ||
addr.c | ||
auth.c | ||
auth_generic.c | ||
auth_null.c | ||
auth_unix.c | ||
backchannel_rqst.c | ||
cache.c | ||
clnt.c | ||
debugfs.c | ||
Kconfig | ||
Makefile | ||
netns.h | ||
rpc_pipe.c | ||
rpcb_clnt.c | ||
sched.c | ||
socklib.c | ||
stats.c | ||
sunrpc.h | ||
sunrpc_syms.c | ||
svc.c | ||
svc_xprt.c | ||
svcauth.c | ||
svcauth_unix.c | ||
svcsock.c | ||
sysctl.c | ||
timer.c | ||
xdr.c | ||
xprt.c | ||
xprtmultipath.c | ||
xprtsock.c |