linux-kernel - [PATCH] ipc: Update semtimedop() to use hrtimer

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Message-Id: <1650333099-27214-1-git-send-email-prakash.sangappa@oracle.com>
Date:   Mon, 18 Apr 2022 18:51:39 -0700
From:   Prakash Sangappa <prakash.sangappa@...cle.com>
To:     linux-kernel@...r.kernel.org
Cc:     akpm@...ux-foundation.org, tglx@...utronix.de,
        peterz@...radead.org, prakash.sangappa@...cle.com
Subject: [PATCH] ipc: Update semtimedop() to use hrtimer

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>
---
 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