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    SubjectRe: please pull from the trivial tree
    On Fri, Dec 01, 2006 at 01:41:18PM +0100, Tim Schmielau wrote:
    > > 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).


    If kernel hackers are expected to already know it's non-atomic we could
    remove the whole comment.

    The comment regarding "volatile" was bogus since "volatile" wouldn't
    help against getting garbage when reading an u64 variable.


    > Tim

    cu
    Adrian

    --

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    "Only a promise," Lao Er said.
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