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[PATCH v3] cifs: Do not modify mid entry after submitting I/O in cifs_call_async

Started byLong Li <longli@exchange.microsoft.com>
First post2017-06-29 00:10 +0200
Last post2017-06-29 00:30 +0200
Articles 2 — 2 participants

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  [PATCH v3] cifs: Do not modify mid entry after submitting I/O in cifs_call_async Long Li <longli@exchange.microsoft.com> - 2017-06-29 00:10 +0200
    Re: [PATCH v3] cifs: Do not modify mid entry after submitting I/O in cifs_call_async Pavel Shilovsky <piastryyy@gmail.com> - 2017-06-29 00:30 +0200

#1677225 — [PATCH v3] cifs: Do not modify mid entry after submitting I/O in cifs_call_async

FromLong Li <longli@exchange.microsoft.com>
Date2017-06-29 00:10 +0200
Subject[PATCH v3] cifs: Do not modify mid entry after submitting I/O in cifs_call_async
Message-ID<tXtjQ-Wu-29@gated-at.bofh.it>
From: Long Li <longli@microsoft.com>

In cifs_call_async, server may respond as soon as I/O is submitted. Because
mid entry is freed on the return path, it should not be modified after I/O
is submitted.

cifs_save_when_sent modifies the sent timestamp in mid entry, and should not
be called after I/O. Call it before I/O.

Signed-off-by: Long Li <longli@microsoft.com>
---
 fs/cifs/transport.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 47a125e..f49b73f 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -536,11 +536,13 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
 	list_add_tail(&mid->qhead, &server->pending_mid_q);
 	spin_unlock(&GlobalMid_Lock);
 
-
+	/* Need to store the time in mid before calling I/O. For call_async,
+	 * I/O response can come back and free the mid entry on another thread.
+	 */
+	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

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#1677236

FromPavel Shilovsky <piastryyy@gmail.com>
Date2017-06-29 00:30 +0200
Message-ID<tXtDb-13b-13@gated-at.bofh.it>
In reply to#1677225
2017-06-28 15:02 GMT-07:00 Long Li <longli@exchange.microsoft.com>:
> From: Long Li <longli@microsoft.com>
>
> In cifs_call_async, server may respond as soon as I/O is submitted. Because
> mid entry is freed on the return path, it should not be modified after I/O
> is submitted.
>
> cifs_save_when_sent modifies the sent timestamp in mid entry, and should not
> be called after I/O. Call it before I/O.
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
>  fs/cifs/transport.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 47a125e..f49b73f 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -536,11 +536,13 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
>         list_add_tail(&mid->qhead, &server->pending_mid_q);
>         spin_unlock(&GlobalMid_Lock);
>
> -
> +       /* Need to store the time in mid before calling I/O. For call_async,
> +        * I/O response can come back and free the mid entry on another thread.
> +        */
> +       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
>
> --
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> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Thanks! Please fix the comment style to

/*
 * ....
 */

Other than that -

Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

--
Best regards,
Pavel Shilovsky

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