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2009-01-06poll: allow f_op->poll to sleepTejun Heo
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>
2008-09-05select: switch select() and poll() over to hrtimersArjan van de Ven
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>
2008-09-05select: add poll_select_set_timeout() and poll_select_copy_remaining() helpersThomas Gleixner
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>
2008-05-01[PATCH] make osf_select() use core_sys_select()Al Viro
... instead of open-coding it Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-09-11Fix select on /proc files without ->pollAlexey Dobriyan
Taneli Vähäkangas <vahakang@cs.helsinki.fi> reported that commit 786d7e1612f0b0adb6046f19b906609e4fe8b1ba 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>
2006-12-04[PATCH] severing poll.h -> mm.hAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2006-03-28[PATCH] Optimize select/poll by putting small data sets on the stackAndi Kleen
Optimize select and poll by a using stack space for small fd sets This brings back an old optimization from Linux 2.0. Using the stack is faster than kmalloc. On a Intel P4 system it speeds up a select of a single pty fd by about 13% (~4000 cycles -> ~3500) It also saves memory because a daemon hanging in select or poll will usually save one or two less pages. This can add up - e.g. if you have 10 daemons blocking in poll/select you save 40KB of memory. I did a patch for this long ago, but it was never applied. This version is a reimplementation of the old patch that tries to be less intrusive. I only did the minimal changes needed for the stack allocation. The cut off point before external memory is allocated is currently at 832bytes. The system calls always allocate this much memory on the stack. These 832 bytes are divided into 256 bytes frontend data (for the select bitmaps of the pollfds) and the rest of the space for the wait queues used by the low level drivers. There are some extreme cases where this won't work out for select and it falls back to allocating memory too early - especially with very sparse large select bitmaps - but the majority of processes who only have a small number of file descriptors should be ok. [TBD: 832/256 might not be the best split for select or poll] I suspect more optimizations might be possible, but they would be more complicated. One way would be to cache the select/poll context over multiple system calls because typically the input values should be similar. Problem is when to flush the file descriptors out though. Signed-off-by: Andi Kleen <ak@suse.de> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-18[PATCH] Add pselect/ppoll system call implementationDavid Woodhouse
The following implementation of ppoll() and pselect() system calls depends on the architecture providing a TIF_RESTORE_SIGMASK flag in the thread_info. These system calls have to change the signal mask during their operation, and signal handlers must be invoked using the new, temporary signal mask. The old signal mask must be restored either upon successful exit from the system call, or upon returning from the invoked signal handler if the system call is interrupted. We can't simply restore the original signal mask and return to userspace, since the restored signal mask may actually block the signal which interrupted the system call. The TIF_RESTORE_SIGMASK flag deals with this by causing the syscall exit path to trap into do_signal() just as TIF_SIGPENDING does, and by causing do_signal() to use the saved signal mask instead of the current signal mask when setting up the stack frame for the signal handler -- or by causing do_signal() to simply restore the saved signal mask in the case where there is no handler to be invoked. The first patch implements the sys_pselect() and sys_ppoll() system calls, which are present only if TIF_RESTORE_SIGMASK is defined. That #ifdef should go away in time when all architectures have implemented it. The second patch implements TIF_RESTORE_SIGMASK for the PowerPC kernel (in the -mm tree), and the third patch then removes the arch-specific implementations of sys_rt_sigsuspend() and replaces them with generic versions using the same trick. The fourth and fifth patches, provided by David Howells, implement TIF_RESTORE_SIGMASK for FR-V and i386 respectively, and the sixth patch adds the syscalls to the i386 syscall table. This patch: Add the pselect() and ppoll() system calls, providing core routines usable by the original select() and poll() system calls and also the new calls (with their semantics w.r.t timeouts). Signed-off-by: David Woodhouse <dwmw2@infradead.org> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!