linux-toradex.git/fs/select.c, branch v3.0.16

select: remove unused MAX_SELECT_SECONDS

2011-03-21T04:16:08+00:00

Remove the leftover from the commit 8ff3e8e85fa6 ("select:
switch select() and poll() over to hrtimers").

Signed-off-by: Namhyung Kim 
Acked-by: Arjan van de Ven 
Signed-off-by: Al Viro

fs/select.c: fix information leak to userspace

2011-01-13T16:03:12+00:00

On some architectures __kernel_suseconds_t is int.  On these archs struct
timeval has padding bytes at the end.  This struct is copied to userspace
with these padding bytes uninitialized.  This leads to leaking of contents
of kernel stack memory.

This bug was added with v2.6.27-rc5-286-gb773ad4.

[akpm@linux-foundation.org: avoid the memset on architectures which don't need it]
Signed-off-by: Vasiliy Kulikov 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

epoll: make epoll_wait() use the hrtimer range feature

2010-10-28T01:03:18+00:00

This make epoll use hrtimers for the timeout value which prevents
epoll_wait() from timing out up to a millisecond early.

This mirrors the behavior of select() and poll().

Signed-off-by: Shawn Bohrer 
Cc: Al Viro 
Acked-by: Davide Libenzi 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

select: rename estimate_accuracy() to select_estimate_accuracy()

2010-10-28T01:03:18+00:00

Make it a subsystem-specific identifier because we wish to amke it
non-static in the next patch ("epoll: make epoll_wait() use the hrtimer
range feature").

Cc: Shawn Bohrer 
Cc: Al Viro 
Cc: Davide Libenzi 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Add generic sys_old_select()

2010-03-12T23:52:32+00:00

Add a generic implementation of the old select() syscall, which expects
its argument in a memory block and switch all architectures over to use
it.

Signed-off-by: Christoph Hellwig 
Cc: Ralf Baechle 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mundt 
Cc: Jeff Dike 
Cc: Hirokazu Takata 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Reviewed-by: H. Peter Anvin 
Cc: Al Viro 
Cc: Arnd Bergmann 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: "Luck, Tony" 
Cc: James Morris 
Acked-by: Andreas Schwab 
Acked-by: Russell King 
Acked-by: Greg Ungerer 
Acked-by: David Howells 
Cc: Andreas Schwab 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: use rlimit helpers

2010-03-06T19:26:29+00:00

Make sure compiler won't do weird things with limits.  E.g.  fetching them
twice may return 2 different values after writable limits are implemented.

I.e.  either use rlimit helpers added in commit 3e10e716abf3 ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby 
Cc: Alexander Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

headers: remove sched.h from poll.h

2009-10-04T22:05:10+00:00

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Linus Torvalds

poll/select: avoid arithmetic overflow in __estimate_accuracy()

2009-09-23T14:39:27+00:00

__estimate_accuracy() was prone to integer overflow, for example if *tv ==
{2147, 483648000} on a 32 bit computer (or even for delays as small as
{429, 500000000} if the task is niced).

Because the result was already forced between 0 and 100ms, the effect of
the overflow was not too problematic, but the use of the hrtimer range
feature was not optimal in overflow cases.

This patch ensures that there can not be an integer overflow in this
function.

Signed-off-by: Guillaume Knispel 
Cc: Alexander Viro 
Cc: Arjan van de Ven 
Cc: Thomas Gleixner 
Cc: Heiko Carstens 
Cc: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

poll/select: initialize triggered field of struct poll_wqueues

2009-08-16T01:40:11+00:00

The triggered field of struct poll_wqueues introduced in commit
5f820f648c92a5ecc771a96b3c29aa6e90013bba ("poll: allow f_op->poll to
sleep").

It was first set to 1 in pollwake() (now __pollwake() ), tested and
later set to 0 in poll_schedule_timeout(), but not initialized before.

As a result when the process needs to sleep, triggered was likely to be
non-zero even if pollwake() is not called before the first
poll_schedule_timeout(), meaning schedule_hrtimeout_range() would not be
called and an extra loop calling all ->poll() would be done.

This patch initialize triggered to 0 in poll_initwait() so the ->poll()
are not called twice before the process goes to sleep when it needs to.

Signed-off-by: Guillaume Knispel 
Acked-by: Thomas Gleixner 
Acked-by: Tejun Heo 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds

poll: avoid extra wakeups in select/poll

2009-06-17T02:47:48+00:00

After introduction of keyed wakeups Davide Libenzi did on epoll, we are
able to avoid spurious wakeups in poll()/select() code too.

For example, typical use of poll()/select() is to wait for incoming
network frames on many sockets.  But TX completion for UDP/TCP frames call
sock_wfree() which in turn schedules thread.

When scheduled, thread does a full scan of all polled fds and can sleep
again, because nothing is really available.  If number of fds is large,
this cause significant load.

This patch makes select()/poll() aware of keyed wakeups and useless
wakeups are avoided.  This reduces number of context switches by about 50%
on some setups, and work performed by sofirq handlers.

Signed-off-by: Eric Dumazet 
Acked-by: David S. Miller 
Acked-by: Andi Kleen 
Acked-by: Ingo Molnar 
Acked-by: Davide Libenzi 
Cc: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds