[PATCH resend] cifs: Do not modify mid entry after submitting I/O in cifs_call_async

[PATCH resend] cifs: Do not modify mid entry after submitting I/O in cifs_call_async

[Long Li]

From: Long Li <longli@microsoft.com>

In cifs_call_async, server response may return as soon as I/O is submitted.
Because mid entry is freed on the return path, do not modify it after I/O is
submitted.

Signed-off-by: Long Li <longli@microsoft.com>
---
 fs/cifs/transport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 47a125e..ba62aaf 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -537,10 +537,10 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
 	spin_unlock(&GlobalMid_Lock);
 
 
+	cifs_save_when_sent(mid);
 	cifs_in_send_inc(server);
 	rc = smb_send_rqst(server, rqst, flags);
 	cifs_in_send_dec(server);
-	cifs_save_when_sent(mid);
 
 	if (rc < 0) {
 		server->sequence_number -= 2;
-- 
2.7.4

Re: [PATCH resend] cifs: Do not modify mid entry after submitting I/O in cifs_call_async

[Pavel Shilovsky]

2017-06-28 11:05 GMT-07:00 Long Li <longli@exchange.microsoft.com>:
> From: Long Li <longli@microsoft.com>
>
> In cifs_call_async, server response may return as soon as I/O is submitted.
> Because mid entry is freed on the return path, do not modify it after I/O is
> submitted.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
>  fs/cifs/transport.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 47a125e..ba62aaf 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -537,10 +537,10 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
>         spin_unlock(&GlobalMid_Lock);
>
>
> +       cifs_save_when_sent(mid);
>         cifs_in_send_inc(server);
>         rc = smb_send_rqst(server, rqst, flags);
>         cifs_in_send_dec(server);
> -       cifs_save_when_sent(mid);
>
>         if (rc < 0) {
>                 server->sequence_number -= 2;
> --
> 2.7.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Looks good. Could you please add an additional comment describing the
behavior in the code?

--
Best regards,
Pavel Shilovsky

RE: [PATCH resend] cifs: Do not modify mid entry after submitting I/O in cifs_call_async

[Long Li]

> -----Original Message-----
> From: Pavel Shilovsky [mailto:piastryyy@gmail.com]
> Sent: Wednesday, June 28, 2017 11:23 AM
> To: Long Li <longli@microsoft.com>
> Cc: Steve French <sfrench@samba.org>; linux-cifs <linux-
> cifs@vger.kernel.org>; samba-technical <samba-technical@lists.samba.org>;
> Kernel Mailing List <linux-kernel@vger.kernel.org>; Long Li
> <longli@microsoft.com>
> Subject: Re: [PATCH resend] cifs: Do not modify mid entry after submitting
> I/O in cifs_call_async
> 
> 2017-06-28 11:05 GMT-07:00 Long Li <longli@exchange.microsoft.com>:
> > From: Long Li <longli@microsoft.com>
> >
> > In cifs_call_async, server response may return as soon as I/O is submitted.
> > Because mid entry is freed on the return path, do not modify it after
> > I/O is submitted.
> >
> > Signed-off-by: Long Li <longli@microsoft.com>
> > ---
> >  fs/cifs/transport.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index
> > 47a125e..ba62aaf 100644
> > --- a/fs/cifs/transport.c
> > +++ b/fs/cifs/transport.c
> > @@ -537,10 +537,10 @@ cifs_call_async(struct TCP_Server_Info *server,
> struct smb_rqst *rqst,
> >         spin_unlock(&GlobalMid_Lock);
> >
> >
> > +       cifs_save_when_sent(mid);
> >         cifs_in_send_inc(server);
> >         rc = smb_send_rqst(server, rqst, flags);
> >         cifs_in_send_dec(server);
> > -       cifs_save_when_sent(mid);
> >
> >         if (rc < 0) {
> >                 server->sequence_number -= 2;
> > --
> > 2.7.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-cifs"
> > in the body of a message to majordomo@vger.kernel.org More
> majordomo
> > info at
> >
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> 
> Looks good. Could you please add an additional comment describing the
> behavior in the code?

Sure, will do.

> 
> --
> Best regards,
> Pavel Shilovsky