Messages in this thread | | | Date | Wed, 26 Jun 2013 09:32:09 +0400 | From | Stanislav Kinsbursky <> | Subject | Re: [PATCH v3 2/4] SUNRPC: fix races on PipeFS UMOUNT notifications |
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25.06.2013 20:13, Myklebust, Trond пишет: > On Mon, 2013-06-24 at 11:52 +0400, Stanislav Kinsbursky wrote: >> CPU#0 CPU#1 >> ----------------------------- ----------------------------- >> rpc_kill_sb >> sn->pipefs_sb = NULL rpc_release_client >> (UMOUNT_EVENT) rpc_free_auth >> rpc_pipefs_event >> rpc_get_client_for_event >> !atomic_inc_not_zero(cl_count) >> <skip the client> >> atomic_inc(cl_count) >> rpc_free_client >> rpc_clnt_remove_pipedir >> <skip client dir removing> >> >> To fix this, this patch does the following: >> >> 1) Calls RPC_PIPEFS_UMOUNT notification with sn->pipefs_sb_lock being held. >> 2) Removes SUNRPC client from the list AFTER pipes destroying. >> 3) Doesn't hold RPC client on notification: if client in the list, then it >> can't be destroyed while sn->pipefs_sb_lock in hold by notification caller. >> >> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> >> Cc: stable@vger.kernel.org >> --- >> net/sunrpc/clnt.c | 5 +---- >> net/sunrpc/rpc_pipe.c | 2 +- >> 2 files changed, 2 insertions(+), 5 deletions(-) > > <snip> > >> diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c >> index c512448..efca2f7 100644 >> --- a/net/sunrpc/rpc_pipe.c >> +++ b/net/sunrpc/rpc_pipe.c >> @@ -1165,7 +1165,6 @@ static void rpc_kill_sb(struct super_block *sb) >> goto out; >> } >> sn->pipefs_sb = NULL; >> - mutex_unlock(&sn->pipefs_sb_lock); >> dprintk("RPC: sending pipefs UMOUNT notification for net %p%s\n", >> net, NET_NAME(net)); >> blocking_notifier_call_chain(&rpc_pipefs_notifier_list, >> @@ -1173,6 +1172,7 @@ static void rpc_kill_sb(struct super_block *sb) >> sb); >> put_net(net); >> out: >> + mutex_unlock(&sn->pipefs_sb_lock); > > Is this safe to do after the put_net()? >
Sure it's not. Sorry. Will send the patch once more.
>> kill_litter_super(sb); >> } >> >> > >
-- Best regards, Stanislav Kinsbursky -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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