Messages in this thread | | | Date | Fri, 1 Dec 2006 13:41:18 +0100 (CET) | From | Tim Schmielau <> | Subject | Re: please pull from the trivial tree |
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> Chase Venters (1): > Fix jiffies.h comment
This one actually obscures the comment rather than fixing it.
From jiffies.h: > 76 /* > 77 * The 64-bit value is not volatile - you MUST NOT read it > 78 * without sampling the sequence number in xtime_lock. > 79 * get_jiffies_64() will do this for you as appropriate. > 80 */ > 81 extern u64 __jiffy_data jiffies_64; > 82 extern unsigned long volatile __jiffy_data jiffies;
Note that jiffies is volatile, while jiffies_64 is not; the comment currently explains that. The proposed patch
> Fix jiffies.h comment > jiffies.h includes a comment informing that jiffies_64 must be read with the > assistance of the xtime_lock seqlock. The comment text, however, calls > jiffies_64 "not volatile", which should probably read "not atomic". > > --- a/include/linux/jiffies.h > +++ b/include/linux/jiffies.h > @@ -74,7 +74,7 @@ > #define __jiffy_data __attribute__((section(".data"))) > /* > - * The 64-bit value is not volatile - you MUST NOT read it > + * The 64-bit value is not atomic - you MUST NOT read it > * without sampling the sequence number in xtime_lock. > * get_jiffies_64() will do this for you as appropriate. > */
would leave a comment that is correct, but less useful (I'd expect any kernel hacker to know that u64 is non-atomic on many platforms).
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