lwn.git/kernel/wait.c, branch v3.13-rc3

sched: Move wait.c into kernel/sched/

2013-11-06T06:49:16+00:00

Suggested-by: Ingo Molnar Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/n/tip-5q5yqvdaen0rmapwloeaotx3@git.kernel.org Signed-off-by: Ingo Molnar

sched/wait: Introduce prepare_to_wait_event()

2013-10-16T12:22:18+00:00

Add the new helper, prepare_to_wait_event() which should only be used by ___wait_event(). prepare_to_wait_event() returns -ERESTARTSYS if signal_pending_state() is true, otherwise it does prepare_to_wait/exclusive. This allows to uninline the signal-pending checks in wait_event*() macros. Also, it can initialize wait->private/func. We do not care if they were already initialized, the values are the same. This also shaves a couple of insns from the inlined code. This obviously makes prepare_*() path a little bit slower, but we are likely going to sleep anyway, so I think it makes sense to shrink .text: text data bss dec hex filename =================================================== before: 5126092 2959248 10117120 18202460 115bf5c vmlinux after: 5124618 2955152 10117120 18196890 115a99a vmlinux on my build. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131007161824.GA29757@redhat.com Signed-off-by: Ingo Molnar

kernel: fix new kernel-doc warning in wait.c

2013-08-19T16:08:54+00:00

Fix new kernel-doc warnings in kernel/wait.c: Warning(kernel/wait.c:374): No description found for parameter 'p' Warning(kernel/wait.c:374): Excess function parameter 'word' description in 'wake_up_atomic_t' Warning(kernel/wait.c:374): Excess function parameter 'bit' description in 'wake_up_atomic_t' Signed-off-by: Randy Dunlap Cc: David Howells Signed-off-by: Linus Torvalds

Fix __wait_on_atomic_t() to call the action func if the counter != 0

2013-07-23T22:46:48+00:00

Fix __wait_on_atomic_t() so that it calls the action func if the counter != 0 rather than if the counter is 0 so as to be analogous to __wait_on_bit(). Thanks to Yacine who found this by visual inspection. This will affect FS-Cache in that it will could fail to sleep correctly when trying to clean up after a netfs cookie is withdrawn. Reported-by: Yacine Belkadi Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: Milosz Tanski Signed-off-by: Linus Torvalds

Add wait_on_atomic_t() and wake_up_atomic_t()

2013-05-15T12:50:38+00:00

Add wait_on_atomic_t() and wake_up_atomic_t() to indicate became-zero events on atomic_t types. This uses the bit-wake waitqueue table. The key is set to a value outside of the number of bits in a long so that wait_on_bit() won't be woken up accidentally. What I'm using this for is: in a following patch I add a counter to struct fscache_cookie to count the number of outstanding operations that need access to netfs data. The way this works is: (1) When a cookie is allocated, the counter is initialised to 1. (2) When an operation wants to access netfs data, it calls atomic_inc_unless() to increment the counter before it does so. If it was 0, then the counter isn't incremented, the operation isn't permitted to access the netfs data (which might by this point no longer exist) and the operation aborts in some appropriate manner. (3) When an operation finishes with the netfs data, it decrements the counter and if it reaches 0, calls wake_up_atomic_t() on it - the assumption being that it was the last blocker. (4) When a cookie is released, the counter is decremented and the releaser uses wait_on_atomic_t() to wait for the counter to become 0 - which should indicate no one is using the netfs data any longer. The netfs data can then be destroyed. There are some alternatives that I have thought of and that have been suggested by Tejun Heo: (A) Using wait_on_bit() to wait on a bit in the counter. This doesn't work because if that bit happens to be 0 then the wait won't happen - even if the counter is non-zero. (B) Using wait_on_bit() to wait on a flag elsewhere which is cleared when the counter reaches 0. Such a flag would be redundant and would add complexity. (C) Adding a waitqueue to fscache_cookie - this would expand that struct by several words for an event that happens just once in each cookie's lifetime. Further, cookies are generally per-file so there are likely to be a lot of them. (D) Similar to (C), but add a pointer to a waitqueue in the cookie instead of a waitqueue. This would add single word per cookie and so would be less of an expansion - but still an expansion. (E) Adding a static waitqueue to the fscache module. Generally this would be fine, but under certain circumstances many cookies will all get added at the same time (eg. NFS umount, cache withdrawal) thereby presenting scaling issues. Note that the wait may be significant as disk I/O may be in progress. So, I think reusing the wait_on_bit() waitqueue set is reasonable. I don't make much use of the waitqueue I need on a per-cookie basis, but sometimes I have a huge flood of the cookies to deal with. I also don't want to add a whole new set of global waitqueue tables specifically for the dec-to-0 event if I can reuse the bit tables. Signed-off-by: David Howells Tested-By: Milosz Tanski Acked-by: Jeff Layton

propagate name change to comments in kernel source

2012-12-06T09:39:54+00:00

I've legally changed my name with New York State, the US Social Security Administration, et al. This patch propagates the name change and change in initials and login to comments in the kernel source as well. Signed-off-by: Nadia Yvette Chambers Signed-off-by: Jiri Kosina

lockdep/waitqueues: Add better annotation

2011-12-21T09:07:39+00:00

-> #2 (&tty->write_wait){-.-...}: is a lot more informative than: -> #2 (key#19){-.....}: Signed-off-by: Peter Zijlstra Cc: Andrew Morton Cc: Linus Torvalds Link: http://lkml.kernel.org/n/tip-8zpopbny51023rdb0qq67eye@git.kernel.org Signed-off-by: Ingo Molnar

kernel: Map most files to use export.h instead of module.h

2011-10-31T13:20:12+00:00

The changed files were only including linux/module.h for the EXPORT_SYMBOL infrastructure, and nothing else. Revector them onto the isolated export header for faster compile times. Nothing to see here but a whole lot of instances of: -#include +#include This commit is only changing the kernel dir; next targets will probably be mm, fs, the arch dirs, etc. Signed-off-by: Paul Gortmaker

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi

docbook: add more wait/wake/completion to device-drivers docbook

2010-10-27T00:32:41+00:00

Add more wait, wake, and completion interfaces to the device-drivers docbook. Fix kernel-doc notation in the added files. Signed-off-by: Randy Dunlap Signed-off-by: Linus Torvalds