svn commit: r366429 - in head/sys: kern sys
Rick Macklem
rmacklem at uoguelph.ca
Sun Oct 4 21:06:16 UTC 2020
Mateusz Guzik wrote:
>Why is the process lock always taken? It looks like both routines just
>check a thread-local flag, so perhaps this can get away without
>serializing this process-wide?
I did spot this slight difference between the initial version of sig_intr() and
this one. At least w.r.t. copy_file_range(2), the call happens infrequently
enough that the overhead of acquiring the lock is not significant.
rick
On 10/4/20, Konstantin Belousov <kib at freebsd.org> wrote:
> Author: kib
> Date: Sun Oct 4 16:33:42 2020
> New Revision: 366429
> URL: https://svnweb.freebsd.org/changeset/base/366429
>
> Log:
> Add sig_intr(9).
>
> It gives the answer would the thread sleep according to current state
> of signals and suspensions. Of course the answer is racy and allows
> for false-negatives (no sleep when signal is delivered after process
> lock is dropped). Also the answer might change due to signal
> rescheduling among threads in multi-threaded process.
>
> Still it is the best approximation I can provide, to answering the
> question was the thread interrupted.
>
> Reviewed by: markj
> Tested by: pho, rmacklem
> Sponsored by: The FreeBSD Foundation
> MFC after: 2 weeks
> Differential revision: https://reviews.freebsd.org/D26628
>
> Modified:
> head/sys/kern/kern_sig.c
> head/sys/sys/signalvar.h
>
> Modified: head/sys/kern/kern_sig.c
> ==============================================================================
> --- head/sys/kern/kern_sig.c Sun Oct 4 16:30:05 2020 (r366428)
> +++ head/sys/kern/kern_sig.c Sun Oct 4 16:33:42 2020 (r366429)
> @@ -3204,6 +3204,24 @@ sig_ast_needsigchk(struct thread *td)
> return (ret);
> }
>
> +int
> +sig_intr(void)
> +{
> + struct thread *td;
> + struct proc *p;
> + int ret;
> +
> + td = curthread;
> + p = td->td_proc;
> +
> + PROC_LOCK(p);
> + ret = sig_ast_checksusp(td);
> + if (ret == 0)
> + ret = sig_ast_needsigchk(td);
> + PROC_UNLOCK(p);
> + return (ret);
> +}
> +
> void
> proc_wkilled(struct proc *p)
> {
>
> Modified: head/sys/sys/signalvar.h
> ==============================================================================
> --- head/sys/sys/signalvar.h Sun Oct 4 16:30:05 2020 (r366428)
> +++ head/sys/sys/signalvar.h Sun Oct 4 16:33:42 2020 (r366429)
> @@ -408,6 +408,7 @@ int sig_ffs(sigset_t *set);
> void sigfastblock_clear(struct thread *td);
> void sigfastblock_fetch(struct thread *td);
> void sigfastblock_setpend(struct thread *td, bool resched);
> +int sig_intr(void);
> void siginit(struct proc *p);
> void signotify(struct thread *td);
> void sigqueue_delete(struct sigqueue *queue, int sig);
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--
Mateusz Guzik <mjguzik gmail.com>
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