On Tue, 2012-07-10 at 14:26 -0500, Shirish Pargaonkar wrote: > On Tue, Jul 10, 2012 at 1:58 PM, Sachin Prabhu <sprabhu@xxxxxxxxxx> wrote: > > A user reported a crash in cifs_demultiplex_thread() caused by an > > incorrectly set mid_q_entry->callback() function. It appears that the > > callback assignment made in cifs_call_async() was not flushed back to > > memory suggesting that a memory barrier was required here. Changing the > > code to make sure that the mid_q_entry structure was completely > > initialised before it was added to the pending queue fixes the problem. > > > > Signed-off-by: Sachin Prabhu <sprabhu@xxxxxxxxxx> > > --- > > fs/cifs/transport.c | 20 ++++++++++---------- > > 1 file changed, 10 insertions(+), 10 deletions(-) > > > > diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c > > index 3097ee5..c5faf02 100644 > > --- a/fs/cifs/transport.c > > +++ b/fs/cifs/transport.c > > @@ -365,14 +365,10 @@ cifs_setup_async_request(struct TCP_Server_Info *server, struct kvec *iov, > > if (mid == NULL) > > return -ENOMEM; > > > > - /* put it on the pending_mid_q */ > > - spin_lock(&GlobalMid_Lock); > > - list_add_tail(&mid->qhead, &server->pending_mid_q); > > - spin_unlock(&GlobalMid_Lock); > > - > > rc = cifs_sign_smb2(iov, nvec, server, &mid->sequence_number); > > if (rc) > > - delete_mid(mid); > > + DeleteMidQEntry(mid); > > + > > *ret_mid = mid; > > Looks correct. But just a thought, why bother assigning ret_mid > a Deleted mid if rc is not null? I did notice this line which was already set to do this when I wrote the patch. Since it did not result in any error, I left it alone. I will create another patch which cleans this bit of the code. Sachin Prabhu > > > return rc; > > } > > @@ -407,17 +403,21 @@ cifs_call_async(struct TCP_Server_Info *server, struct kvec *iov, > > mid->callback_data = cbdata; > > mid->mid_state = MID_REQUEST_SUBMITTED; > > > > + /* put it on the pending_mid_q */ > > + spin_lock(&GlobalMid_Lock); > > + list_add_tail(&mid->qhead, &server->pending_mid_q); > > + spin_unlock(&GlobalMid_Lock); > > + > > + > > cifs_in_send_inc(server); > > rc = smb_sendv(server, iov, nvec); > > cifs_in_send_dec(server); > > cifs_save_when_sent(mid); > > mutex_unlock(&server->srv_mutex); > > > > - if (rc) > > - goto out_err; > > + if (rc == 0) > > + return 0; > > > > - return rc; > > -out_err: > > delete_mid(mid); > > add_credits(server, 1); > > wake_up(&server->request_q); > > -- > > 1.7.10.4 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-cifs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
