* [PATCH v2] ipc: Update semtimedop() to use hrtimer
@ 2022-04-28 15:07 Prakash Sangappa
2022-04-28 19:26 ` Thomas Gleixner
0 siblings, 1 reply; 2+ messages in thread
From: Prakash Sangappa @ 2022-04-28 15:07 UTC (permalink / raw)
To: linux-kernel; +Cc: tglx, akpm, peterz, dave, manfred, Prakash Sangappa
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.
v1->v2:
- Use timespec64_valid() to validate timeout
and other changes as suggested by Thomas Gleixner
Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com>
---
ipc/sem.c | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index 0dbdb98..44b65b6 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1995,7 +1995,9 @@ 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, *exp = NULL;
+ bool timed_out = false;
if (nsops < 1 || semid < 0)
return -EINVAL;
@@ -2003,12 +2005,11 @@ long __do_semtimedop(int semid, struct sembuf *sops,
return -E2BIG;
if (timeout) {
- if (timeout->tv_sec < 0 || timeout->tv_nsec < 0 ||
- timeout->tv_nsec >= 1000000000L) {
- error = -EINVAL;
- goto out;
- }
- jiffies_left = timespec64_to_jiffies(timeout);
+ if (!timespec64_valid(timeout))
+ return -EINVAL;
+ expires = ktime_add_safe(ktime_get(),
+ timespec64_to_ktime(*timeout));
+ exp = &expires;
}
@@ -2166,10 +2167,8 @@ long __do_semtimedop(int semid, struct sembuf *sops,
sem_unlock(sma, locknum);
rcu_read_unlock();
- if (timeout)
- jiffies_left = schedule_timeout(jiffies_left);
- else
- schedule();
+ timed_out = !schedule_hrtimeout_range(exp,
+ current->timer_slack_ns, HRTIMER_MODE_ABS);
/*
* fastpath: the semop has completed, either successfully or
@@ -2210,7 +2209,7 @@ 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 (timed_out)
error = -EAGAIN;
} while (error == -EINTR && !signal_pending(current)); /* spurious */
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] ipc: Update semtimedop() to use hrtimer
2022-04-28 15:07 [PATCH v2] ipc: Update semtimedop() to use hrtimer Prakash Sangappa
@ 2022-04-28 19:26 ` Thomas Gleixner
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Gleixner @ 2022-04-28 19:26 UTC (permalink / raw)
To: Prakash Sangappa, linux-kernel
Cc: akpm, peterz, dave, manfred, Prakash Sangappa
Prakash,
On Thu, Apr 28 2022 at 08:07, Prakash Sangappa 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.
almost perfect :)
The v1->v2: description wants to be below the '---' separator. It's not
part of the changelog and just helpful for reviewers to assess the
history of the patch(set).
> v1->v2:
> - Use timespec64_valid() to validate timeout
> and other changes as suggested by Thomas Gleixner
>
> Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com>
> ---
...
> @@ -2210,7 +2209,7 @@ 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 (timed_out)
> error = -EAGAIN;
> } while (error == -EINTR && !signal_pending(current)); /* spurious */
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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