Messages in this thread | | | Date | Fri, 20 Apr 2012 08:51:50 +0200 | From | Andreas Herz <> | Subject | msecs_to_jiffies() still returns values greater then MAX_JIFFY_OFFSET |
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Hi,
i'm new to the LKML and so i couldn't reply to the old mail from Mar 2011.
On 29 Mar 2011 there was already a disucssion about this issue:
http://lkml.org/lkml/2011/3/29/262
The problem still exists, as /kernel/time.c wasn't patched. I stumbled upon this "bug" when i modified the ipset sourcecode that uses msecs_to_jiffies() for timeout calculations.
When i call msecs_to_jiffies(2147483000) the return value is 2147483000 on my x86 32-Bit System with 1000Hz. When i call the function with msecs_to_jiffies(2147484000) the return value is MAX_JIFFY_OFFSET what's 1073741822 on my system. That isn't the behaviour i expect from this comment in time.c:
* - 'too large' values [that would result in larger than * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
So you can pass values greater then MAX_JIFFY_OFFSET up to INT_MAX in this example although the limit should be at INT_MAX/2 for MAX_JIFFY_OFFSET.
I'm not sure if the solution is to increase MAX_JIFFY_OFFSET or to catch values between this gap. I also don't understand why the function returns a unsigned long but is limited to integer. It could be nice to increase the values that can be handled with this function.
Greetings
-- Andreas Herz
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