The patch titled Documentation/volatile-considered-harmful.txt: correct cpu_relax() documentation has been added to the -mm tree. Its filename is documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: Documentation/volatile-considered-harmful.txt: correct cpu_relax() documentation From: Russell King <rmk@xxxxxxxxxxxxxxxx> cpu_relax() is documented in volatile-considered-harmful.txt to be a memory barrier. However, everyone with the exception of Blackfin and possibly ia64 defines cpu_relax() to be a compiler barrier. Make the documentation reflect the general concensus. Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> Cc: <linux-arch@xxxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/volatile-considered-harmful.txt | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff -puN Documentation/volatile-considered-harmful.txt~documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation Documentation/volatile-considered-harmful.txt --- a/Documentation/volatile-considered-harmful.txt~documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation +++ a/Documentation/volatile-considered-harmful.txt @@ -63,9 +63,9 @@ way to perform a busy wait is: cpu_relax(); The cpu_relax() call can lower CPU power consumption or yield to a -hyperthreaded twin processor; it also happens to serve as a memory barrier, -so, once again, volatile is unnecessary. Of course, busy-waiting is -generally an anti-social act to begin with. +hyperthreaded twin processor; it also happens to serve as a compiler +barrier, so, once again, volatile is unnecessary. Of course, busy- +waiting is generally an anti-social act to begin with. There are still a few rare situations where volatile makes sense in the kernel: _ Patches currently in -mm which might be from rmk@xxxxxxxxxxxxxxxx are origin.patch documentation-volatile-considered-harmfultxt-correct-cpu_relax-documentation.patch arm-convert-proc-cpu-aligment-to-seq_file.patch arch-arm-include-asm-elfh-forward-declare-the-task-struct.patch bitops-rename-for_each_bit-to-for_each_set_bit-mtd.patch -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html