linux-kernel - [RFC/PATCH] 2.6.24-rcx: Make sys_poll() wait at least timeout ms

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Message-Id: <200712181831.24202.fzu@wemgehoertderstaat.de>
Date:	Tue, 18 Dec 2007 18:31:23 +0100
From:	Karsten Wiese <fzu@...gehoertderstaat.de>
To:	linux-kernel@...r.kernel.org
Subject: [RFC/PATCH] 2.6.24-rcx: Make sys_poll() wait at least timeout ms

Hi,

while playing with jackd on 2.6.24-rcx, I found poll() timing out too early.
That is: earlier than its timeout argument specified.
Setting poll()'s timeout argument to "required timeout" + "1 jiffy in ms"
fixed it. Patch below should fix it too. Correct?
Untested.
Otherwise 2.6.24-rc5 ticks just fine here, thanks.

      Karsten
 
------------->
Make sys_poll() wait at least timeout ms

schedule_timeout(jiffies) waits for at least jiffies - 1.
Add 1 jiffie to the timeout_jiffies calculated in sys_poll() to wait at least
timeout_msecs, like poll() manpage says.

Signed-off-by: Karsten Wiese <fzu@...gehoertderstaat.de>
---
 fs/select.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/select.c b/fs/select.c
index 47f4792..5633fe9 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -739,7 +739,7 @@ asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
 			timeout_jiffies = -1;
 		else
 #endif
-			timeout_jiffies = msecs_to_jiffies(timeout_msecs);
+			timeout_jiffies = msecs_to_jiffies(timeout_msecs) + 1;
 	} else {
 		/* Infinite (< 0) or no (0) timeout */
 		timeout_jiffies = timeout_msecs;
-- 
1.5.3.6

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