Messages in this thread | | | Date | Thu, 30 Jan 2020 12:33:41 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] exit.c: Fix Sparse errors and warnings |
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On 01/30, Christian Brauner wrote: > > On Thu, Jan 30, 2020 at 11:50:28AM +0530, madhuparnabhowmik10@gmail.com wrote: > > From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> > > > > This patch fixes the following sparse error: > > kernel/exit.c:627:25: error: incompatible types in comparison expression > > > > And the following warning: > > kernel/exit.c:626:40: warning: incorrect type in assignment > > > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> > > I think the previous version was already fine but hopefully > RCU_INIT_POINTER() really saves some overhead. In any case:
It is not about overhead, RCU_INIT_POINTER() documents the fact that we didn't make any changes to the new parent, we only need to change the pointer.
And btw, I don't really understand the __rcu annotations. Say, according to sparse this code is wrong:
int __rcu *P;
void func(int *p) { P = p; }
OK, although quite possibly it is fine.
However, this code
int __rcu *P;
void func(int __rcu *p) { *p = 10; P = p; }
is almost certainly wrong but sparse is happy, asn is the same.
> Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
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