- 26 Jul, 2007 1 commit
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Davide Libenzi authored
Davi fixed a missing cast in the __put_user(), that was making timerfd return a single byte instead of the full value. Talking with Michael about the timerfd man page, we think it'd be better to use a u64 for the returned value, to align it with the eventfd implementation. This is an ABI change. The timerfd code is new in 2.6.22 and if we merge this into 2.6.23 then we should also merge it into 2.6.22.x. That will leave a few early 2.6.22 kernels out in the wild which might misbehave when a future timerfd-enabled glibc is run on them. mtk says: The difference would be that read() will only return 4 bytes, while the application will expect 8. If the application is checking the size of returned value, as it should, then it will be able to detect the problem (it could even be sophisticated enough to know that if this is a 4-byte return, then it is running on an old 2.6.22 kernel). If the application is not checking the return from read(), then its 8-byte buffer will not be filled -- the contents of the last 4 bytes will be undefined, so the u64 value as a whole will be junk. Signed-off-by:
Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Davi Arnaut <davi@haxent.com.br> Cc: <stable@kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- 18 May, 2007 1 commit
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Davide Libenzi authored
The timerfd was using the unlocked waitqueue operations, but it was using a different lock, so poll_wait() would race with it. This makes timerfd directly use the waitqueue lock. Signed-off-by:
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- 11 May, 2007 1 commit
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Davide Libenzi authored
This patch introduces a new system call for timers events delivered though file descriptors. This allows timer event to be used with standard POSIX poll(2), select(2) and read(2). As a consequence of supporting the Linux f_op->poll subsystem, they can be used with epoll(2) too. The system call is defined as: int timerfd(int ufd, int clockid, int flags, const struct itimerspec *utmr); The "ufd" parameter allows for re-use (re-programming) of an existing timerfd w/out going through the close/open cycle (same as signalfd). If "ufd" is -1, s new file descriptor will be created, otherwise the existing "ufd" will be re-programmed. The "clockid" parameter is either CLOCK_MONOTONIC or CLOCK_REALTIME. The time specified in the "utmr->it_value" parameter is the expiry time for the timer. If the TFD_TIMER_ABSTIME flag is set in "flags", this is an absolute time, otherwise it's a relative time. If the time specified in the "utmr->it_interval" is not zero (.tv_sec == 0, tv_nsec == 0), this is the period at which the following ticks should be generated. The "utmr->it_interval" should be set to zero if only one tick is requested. Setting the "utmr->it_value" to zero will disable the timer, or will create a timerfd without the timer enabled. The function returns the new (or same, in case "ufd" is a valid timerfd descriptor) file, or -1 in case of error. As stated before, the timerfd file descriptor supports poll(2), select(2) and epoll(2). When a timer event happened on the timerfd, a POLLIN mask will be returned. The read(2) call can be used, and it will return a u32 variable holding the number of "ticks" that happened on the interface since the last call to read(2). The read(2) call supportes the O_NONBLOCK flag too, and EAGAIN will be returned if no ticks happened. A quick test program, shows timerfd working correctly on my amd64 box: http://www.xmailserver.org/timerfd-test.c [akpm@linux-foundation.org: add sys_timerfd to sys_ni.c] Signed-off-by:
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