Not a single architecture has wired up sys_pselect7 plus it is the
only system call with seven parameters. Just make it static and
rename it to do_pselect which will do the work for sys_pselect6.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Since we (Analog Devices) updated our Blackfin kernel to 2.6.28, we've
seen occasional 5-second hangs from telnet. telnetd calls select with a
NULL timeout, but with the new kernel, the system call occasionally
returns 0, which causes telnet to call sleep (5). This did not happen
with earlier kernels.
The code in sys_pselect7 looks a bit strange, in particular the variable
"to" is initialized to NULL, then changed if a non-null timeout was
passed in, but not used further. It needs to be passed to
core_sys_select instead of &end_time.
This bug was introduced by 8ff3e8e85f
("select: switch select() and poll() over to hrtimers").
Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>
Reviewed-by: Ulrich Drepper <drepper@redhat.com>
Tested-by: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
f_op->poll is the only vfs operation which is not allowed to sleep. It's
because poll and select implementation used task state to synchronize
against wake ups, which doesn't have to be the case anymore as wait/wake
interface can now use custom wake up functions. The non-sleep restriction
can be a bit tricky because ->poll is not called from an atomic context
and the result of accidentally sleeping in ->poll only shows up as
temporary busy looping when the timing is right or rather wrong.
This patch converts poll/select to use custom wake up function and use
separate triggered variable to synchronize against wake up events. The
only added overhead is an extra function call during wake up and
negligible.
This patch removes the one non-sleep exception from vfs locking rules and
is beneficial to userland filesystem implementations like FUSE, 9p or
peculiar fs like spufs as it's very difficult for those to implement
non-sleeping poll method.
While at it, make the following cosmetic changes to make poll.h and
select.c checkpatch friendly.
* s/type * symbol/type *symbol/ : three places in poll.h
* remove blank line before EXPORT_SYMBOL() : two places in select.c
Oleg: spotted missing barrier in poll_schedule_timeout()
Davide: spotted missing write barrier in pollwake()
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Brad Boyer <flar@allandria.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Roland McGrath <roland@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some userland apps seem to pass in a "0" for the seconds, and several
seconds worth of usecs to select(). The old kernels accepted this just
fine, so the new kernels must too.
However, due to the upscaling of the microseconds to nanoseconds we had
some cases where we got math overflow, and depending on the GCC version
(due to inlining decisions) that actually resulted in an -EINVAL return.
This patch fixes this by adding the excess microseconds to the seconds
field.
Also with thanks to Marcin Slusarz for spotting some implementation bugs
in the diagnostics patches.
Reported-by: Carlos R. Mafra <crmafra2@gmail.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
the slack estimator used unsigned math; however for very short delay it's
possible that by the time you calculate the timeout, it's already passed and
you get a negative time/slack... in an unsigned variable... which then gets
turned into a 100 msec delay rather than zero.
This patch fixes this by using a signed typee in the right places.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
This patch makes the select() and poll() hrtimers use the new range
feature and settings from the task struct.
In addition, this includes the estimate_accuracy() function that Linus
posted to lkml, but changed entirely based on other peoples lkml feedback.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
With lots of help, input and cleanups from Thomas Gleixner
This patch switches select() and poll() over to hrtimers.
The core of the patch is replacing the "s64 timeout" with a
"struct timespec end_time" in all the plumbing.
But most of the diffstat comes from using the just introduced helpers:
poll_select_set_timeout
poll_select_copy_remaining
timespec_add_safe
which make manipulating the timespec easier and less error-prone.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch adds 2 helpers that will be used for the hrtimer based select/poll:
poll_select_set_timeout() is a helper that takes a timeout (as a second, nanosecond
pair) and turns that into a "struct timespec" that represents the absolute end time.
This is a common operation in the many select() and poll() variants and needs various,
common, sanity checks.
poll_select_copy_remaining() is a helper that takes care of copying the remaining
time to userspace, as select(), pselect() and ppoll() do. This function comes in
both a natural and a compat implementation (due to datastructure differences).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Christian Borntraeger reported that reinstating cond_resched() with
CONFIG_PREEMPT caused a performance regression on lmbench:
For example select file 500:
23 microseconds
32 microseconds
and that's really because we totally unnecessarily do the cond_resched()
in the innermost loop of select(), which is just silly.
This moves it out from the innermost loop (which only ever loops ove the
bits in a single "unsigned long" anyway), which makes the performance
regression go away.
Reported-and-tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These are small cleanups all over the tree.
Trivial style and comment changes to
fs/select.c, kernel/signal.c, kernel/stop_machine.c & mm/pdflush.c
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Lomesh reported poll returning EINTR during suspend/resume cycle. This is
caused by the STOP/CONT cycle that the freezer uses, generating a pending
signal for what in effect is an ignored signal. In general poll is a
little eager in returning EINTR, when it could try not bother userspace and
simply restart the syscall. Both select and ppoll do use ERESTARTNOHAND to
restart the syscall. Oleg points out that simply using ERESTARTNOHAND will
cause poll to restart with original timeout value. which could ultimately
lead to process never returning to userspace. Instead use
ERESTART_RESTARTBLOCK, and restart poll with updated timeout value.
Inspired by Manfred's use ERESTARTNOHAND in poll patch.
[bunk@kernel.org: do_restart_poll() can become static]
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Agarwal, Lomesh" <lomesh.agarwal@intel.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cleanup. Lessens both the source and compiled code (100 bytes) and imho makes
the code much more understandable.
With this patch "struct poll_list *head" always points to on-stack stack_pps,
so we can remove all "is it on-stack" and "was it initialized" checks.
Also, move poll_initwait/poll_freewait and -EINTR detection closer to the
do_poll()'s callsite.
[akpm@linux-foundation.org: fix warning (size_t != uint)]
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Looks-good-to: Andi Kleen <ak@suse.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Vadim Lobanov <vlobanov@speakeasy.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Taneli Vähäkangas <vahakang@cs.helsinki.fi> reported that commit
786d7e1612 aka "Fix rmmod/read/write races
in /proc entries" broke SBCL + SLIME combo.
The old code in do_select() used DEFAULT_POLLMASK, if couldn't find
->poll handler. The new code makes ->poll always there and returns 0 by
default, which is not correct. Return DEFAULT_POLLMASK instead.
Steps to reproduce:
install emacs, SBCL, SLIME
emacs
M-x slime in *inferior-lisp* buffer
[watch it doing "Connecting to Swank on port X.."]
Please, apply before 2.6.23.
P.S.: why SBCL can't just read(2) /proc/cpuinfo is a mystery.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: T Taneli Vahakangas <vahakang@cs.helsinki.fi>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
