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Date: Mon, 25 Apr 2022 13:50:53 -0700 From: Andrew Morton <akpm@...ux-foundation.org> To: Prakash Sangappa <prakash.sangappa@...cle.com> Cc: LKML <linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>, Davidlohr Bueso <dave@...olabs.net>, Manfred Spraul <manfred@...orfullife.com> Subject: Re: [PATCH] ipc: Update semtimedop() to use hrtimer On Mon, 25 Apr 2022 19:38:44 +0000 Prakash Sangappa <prakash.sangappa@...cle.com> wrote: > > > > On Apr 18, 2022, at 6:51 PM, Prakash Sangappa <prakash.sangappa@...cle.com> wrote: > > > > semtimedop() should be converted to use hrtimer like it has been > > done for most of the system calls with timeouts. This system call > > already takes a struct timespec as an argument and can therefore > > provide finer granularity timed wait. > > > > Signed-off-by: Prakash Sangappa <prakash.sangappa@...cle.com> > > Can I get a review of this patch? That would be nice. I looked at it, seemed OK. Perhaps the usual IPC developers (Davidlohr and Manfred) can comment? > Note this patch has been added to Andrew's mm tree. > > > > --- > > ipc/sem.c | 15 +++++++++++---- > > 1 file changed, 11 insertions(+), 4 deletions(-) > > > > diff --git a/ipc/sem.c b/ipc/sem.c > > index 0dbdb98..6cd1a1b8 100644 > > --- a/ipc/sem.c > > +++ b/ipc/sem.c > > @@ -1995,7 +1995,10 @@ long __do_semtimedop(int semid, struct sembuf *sops, > > int max, locknum; > > bool undos = false, alter = false, dupsop = false; > > struct sem_queue queue; > > - unsigned long dup = 0, jiffies_left = 0; > > + unsigned long dup = 0; > > + ktime_t expires; > > + int timed_out = 0; > > + struct timespec64 end_time; > > > > if (nsops < 1 || semid < 0) > > return -EINVAL; > > @@ -2008,7 +2011,9 @@ long __do_semtimedop(int semid, struct sembuf *sops, > > error = -EINVAL; > > goto out; > > } > > - jiffies_left = timespec64_to_jiffies(timeout); > > + ktime_get_ts64(&end_time); > > + end_time = timespec64_add_safe(end_time, *timeout); > > + expires = timespec64_to_ktime(end_time); > > } > > > > > > @@ -2167,7 +2172,9 @@ long __do_semtimedop(int semid, struct sembuf *sops, > > rcu_read_unlock(); > > > > if (timeout) > > - jiffies_left = schedule_timeout(jiffies_left); > > + timed_out = !schedule_hrtimeout_range(&expires, > > + current->timer_slack_ns, > > + HRTIMER_MODE_ABS); > > else > > schedule(); > > > > @@ -2210,7 +2217,7 @@ long __do_semtimedop(int semid, struct sembuf *sops, > > /* > > * If an interrupt occurred we have to clean up the queue. > > */ > > - if (timeout && jiffies_left == 0) > > + if (timeout && timed_out) > > error = -EAGAIN; > > } while (error == -EINTR && !signal_pending(current)); /* spurious */ > > > > -- > > 2.7.4 > > >
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