Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sun, 8 May 2011 07:26:23 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] fs: avoid unecessary smp_wmb() in dup_fd() |
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On Sat, May 07, 2011 at 08:30:01AM +0200, Eric Dumazet wrote: > While copying old_fds array to new_fds, we dont need > rcu_assign_pointer() and its smp_wmb(), since we are the only thread > populating new_fds at this point. > > A bit later, rcu_assign_pointer(newf->fdt, new_fdt) makes sure > our writes are committed to memory before new_fds content is visible to > other threads. > > This removes following sparse warning : > > fs/file.c:371:3: warning: incorrect type in assignment (different > address spaces) > fs/file.c:371:3: expected struct file *<noident> > fs/file.c:371:3: got struct file [noderef] <asn:4>*<noident>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> > Cc: Matthew Wilcox <matthew@wil.cx> > Cc: linux-fsdevel@vger.kernel.org > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Changli Gao <xiaosuo@gmail.com> > Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > --- > fs/file.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/file.c b/fs/file.c > index 4c6992d..8320a8e 100644 > --- a/fs/file.c > +++ b/fs/file.c > @@ -368,7 +368,7 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) > */ > FD_CLR(open_files - i, new_fdt->open_fds); > } > - rcu_assign_pointer(*new_fds++, f); > + *new_fds++ = f; > } > spin_unlock(&oldf->file_lock); > > >
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