linux-kernel - [ 42/59] tcm_fc: Add abort flag for gracefully handling exchange timeout

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Date:	Wed, 11 Apr 2012 16:11:17 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Mark Rustad <mark.d.rustad@...el.com>,
	Kiran Patil <Kiran.patil@...el.com>,
	Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [ 42/59] tcm_fc: Add abort flag for gracefully handling exchange timeout

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Rustad <mark.d.rustad@...el.com>

commit e1c4038282c7586c3544542b37872c434669d3ac upstream.

Add abort flag and use it to terminate processing when an exchange
is timed out or is reset. The abort flag is used in place of the
transport_generic_free_cmd function call in the reset and timeout
cases, because calling that function in that context would free
memory that was in use. The aborted flag allows the lifetime to
be managed in a more normal way, while truncating the processing.

This change eliminates a source of memory corruption which
manifested in a variety of ugly ways.

(nab: Drop unused struct fc_exch *ep in ft_recv_seq)

Signed-off-by: Mark Rustad <mark.d.rustad@...el.com>
Acked-by: Kiran Patil <Kiran.patil@...el.com>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/target/tcm_fc/tcm_fc.h  |    1 +
 drivers/target/tcm_fc/tfc_cmd.c |   10 ++++++++--
 drivers/target/tcm_fc/tfc_io.c  |    2 ++
 3 files changed, 11 insertions(+), 2 deletions(-)

--- a/drivers/target/tcm_fc/tcm_fc.h
+++ b/drivers/target/tcm_fc/tcm_fc.h
@@ -124,6 +124,7 @@ struct ft_cmd {
 	/* Local sense buffer */
 	unsigned char ft_sense_buffer[TRANSPORT_SENSE_BUFFER];
 	u32 was_ddp_setup:1;		/* Set only if ddp is setup */
+	u32 aborted:1;			/* Set if aborted by reset or timeout */
 	struct scatterlist *sg;		/* Set only if DDP is setup */
 	u32 sg_cnt;			/* No. of item in scatterlist */
 };
--- a/drivers/target/tcm_fc/tfc_cmd.c
+++ b/drivers/target/tcm_fc/tfc_cmd.c
@@ -130,6 +130,8 @@ int ft_queue_status(struct se_cmd *se_cm
 	struct fc_exch *ep;
 	size_t len;
 
+	if (cmd->aborted)
+		return 0;
 	ft_dump_cmd(cmd, __func__);
 	ep = fc_seq_exch(cmd->seq);
 	lport = ep->lp;
@@ -196,6 +198,8 @@ int ft_write_pending(struct se_cmd *se_c
 
 	ft_dump_cmd(cmd, __func__);
 
+	if (cmd->aborted)
+		return 0;
 	ep = fc_seq_exch(cmd->seq);
 	lport = ep->lp;
 	fp = fc_frame_alloc(lport, sizeof(*txrdy));
@@ -266,10 +270,10 @@ static void ft_recv_seq(struct fc_seq *s
 	struct ft_cmd *cmd = arg;
 	struct fc_frame_header *fh;
 
-	if (IS_ERR(fp)) {
+	if (unlikely(IS_ERR(fp))) {
 		/* XXX need to find cmd if queued */
 		cmd->seq = NULL;
-		transport_generic_free_cmd(&cmd->se_cmd, 0);
+		cmd->aborted = true;
 		return;
 	}
 
@@ -447,6 +451,8 @@ int ft_queue_tm_resp(struct se_cmd *se_c
 	struct se_tmr_req *tmr = se_cmd->se_tmr_req;
 	enum fcp_resp_rsp_codes code;
 
+	if (cmd->aborted)
+		return 0;
 	switch (tmr->response) {
 	case TMR_FUNCTION_COMPLETE:
 		code = FCP_TMF_CMPL;
--- a/drivers/target/tcm_fc/tfc_io.c
+++ b/drivers/target/tcm_fc/tfc_io.c
@@ -84,6 +84,8 @@ int ft_queue_data_in(struct se_cmd *se_c
 	void *from;
 	void *to = NULL;
 
+	if (cmd->aborted)
+		return 0;
 	ep = fc_seq_exch(cmd->seq);
 	lport = ep->lp;
 	cmd->seq = lport->tt.seq_start_next(cmd->seq);


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