Messages in this thread |  | | | Date | Tue, 12 Feb 2008 08:57:14 +0000 | | From | Jarek Poplawski <> | | Subject | Re: [PATCH] fib_trie: rcu_assign_pointer warning fix |
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On 12-02-2008 02:16, David Miller wrote: > From: Stephen Hemminger <shemminger@vyatta.com> > Date: Mon, 11 Feb 2008 16:59:54 -0800 > > linux-kernel added to CC:, any change to generic kernel infrastructure > should be posted there > >> Eliminate warnings when rcu_assign_pointer is used with unsigned long. >> It is reasonable to use RCU with non-pointer values so allow it for general >> use. Add a comment to explain the if test. >> >> Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> >> --- >> include/linux/rcupdate.h | 13 +++++++------ >> 1 files changed, 7 insertions(+), 6 deletions(-) >> >> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h >> index 37a642c..c44ac87 100644 >> --- a/include/linux/rcupdate.h >> +++ b/include/linux/rcupdate.h >> @@ -172,14 +172,15 @@ struct rcu_head { >> * structure after the pointer assignment. More importantly, this >> * call documents which pointers will be dereferenced by RCU read-side >> * code. >> + * >> + * If value is the NULL (constant 0), then no barrier is needed. >> */ >> >> -#define rcu_assign_pointer(p, v) \ >> - ({ \ >> - if (!__builtin_constant_p(v) || \ >> - ((v) != NULL)) \ >> - smp_wmb(); \ >> - (p) = (v); \ >> +#define rcu_assign_pointer(p, v) \ >> + ({ \ >> + if (!(__builtin_constant_p(v) && v)) \
...But, "If value is the NULL (constant 0)" we have:
if (!(1 && NULL != 0)) ==> if (!(0)) and the barrier is used?! >> + smp_wmb(); \ >> + (p) = (v); \ >> }) >> >> /**
Regards, Jarek P.
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