[PATCH 34/35] libfc: reduce can_queue for all FCP frame allocation failures

Robert Love
2009-09-11T23:59:57Z

From: Vasu Dev <vasu.dev@intel.com>

Currently can_queue is reduced only if frame alloc fails
during fc_fcp_send_data but frame alloc can fail at several
other places in FCP data path and can_queue needs to be
reduced for any FCP frame alloc failure.

This patch adds fc_fcp_frame_alloc for all FCP frame allocations
and if fc_frame_alloc fails in fc_fcp_frame_alloc then reduce
can_queue in fc_fcp_frame_alloc, this will reduce can_queue for
all FCP frame alloc failures.

This required moving fc_fcp_reduce_can_queue up, to build without
adding its prototype. Also renamed fc_fcp_reduce_can_queue to
fc_fcp_can_queue_ramp_down.

Removes fc_fcp_reduce_can_queue calling from fc_fcp_recv since
not needed with added fc_fcp_frame_alloc reducing can_queue.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
---

drivers/scsi/libfc/fc_fcp.c | 102 +++++++++++++++++++++++++------------------
1 files changed, 59 insertions(+), 43 deletions(-)

diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
index e85dc9a..8b7950f 100644
--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -327,6 +327,57 @@ static void fc_fcp_ddp_done(struct fc_fcp_pkt *fsp)
}

/**
+ * fc_fcp_can_queue_ramp_down() - reduces can_queue
+ * @lport: lport to reduce can_queue
+ *
+ * If we are getting memory allocation failures, then we may
+ * be trying to execute too many commands. We let the running
+ * commands complete or timeout, then try again with a reduced
+ * can_queue. Eventually we will hit the point where we run
+ * on all reserved structs.
+ */
+static void fc_fcp_can_queue_ramp_down(struct fc_lport *lport)
+{
+ struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
+ unsigned long flags;
+ int can_queue;
+
+ spin_lock_irqsave(lport->host->host_lock, flags);
+ if (si->throttled)
+ goto done;
+ si->throttled = 1;
+
+ can_queue = lport->host->can_queue;
+ can_queue >>= 1;
+ if (!can_queue)
+ can_queue = 1;
+ lport->host->can_queue = can_queue;
+ shost_printk(KERN_ERR, lport->host, "libfc: Could not allocate frame.\n"
+ "Reducing can_queue to %d.\n", can_queue);
+done:
+ spin_unlock_irqrestore(lport->host->host_lock, flags);
+}
+
+/*
+ * fc_fcp_frame_alloc() - Allocates fc_frame structure and buffer.
+ * @lport: fc lport struct
+ * @len: payload length
+ *
+ * Allocates fc_frame structure and buffer but if fails to allocate
+ * then reduce can_queue.
+ */
+static inline struct fc_frame *fc_fcp_frame_alloc(struct fc_lport *lport,
+ size_t len)
+{
+ struct fc_frame *fp;
+
+ fp = fc_frame_alloc(lport, len);
+ if (!fp)
+ fc_fcp_can_queue_ramp_down(lport);
+ return fp;
+}
+
+/**
* fc_fcp_recv_data() - Handler for receiving SCSI-FCP data from a target
* @fsp: The FCP packet the data is on
* @fp: The data frame
@@ -615,38 +666,6 @@ static void fc_fcp_abts_resp(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
}

/**
- * fc_fcp_reduce_can_queue() - Reduce the can_queue value for a local port
- * @lport: The local port to reduce can_queue on
- *
- * If we are getting memory allocation failures, then we may
- * be trying to execute too many commands. We let the running
- * commands complete or timeout, then try again with a reduced
- * can_queue. Eventually we will hit the point where we run
- * on all reserved structs.
- */
-static void fc_fcp_reduce_can_queue(struct fc_lport *lport)
-{
- struct fc_fcp_internal *si = fc_get_scsi_internal(lport);
- unsigned long flags;
- int can_queue;
-
- spin_lock_irqsave(lport->host->host_lock, flags);
- if (si->throttled)
- goto done;
- si->throttled = 1;
-
- can_queue = lport->host->can_queue;
- can_queue >>= 1;
- if (!can_queue)
- can_queue = 1;
- lport->host->can_queue = can_queue;
- shost_printk(KERN_ERR, lport->host, "libfc: Could not allocate frame.\n"
- "Reducing can_queue to %d.\n", can_queue);
-done:
- spin_unlock_irqrestore(lport->host->host_lock, flags);
-}
-
-/**
* fc_fcp_recv() - Reveive an FCP frame
* @seq: The sequence the frame is on
* @fp: The received frame
@@ -664,8 +683,10 @@ static void fc_fcp_recv(struct fc_seq *seq, struct fc_frame *fp, void *arg)
u8 r_ctl;
int rc = 0;

- if (IS_ERR(fp))
- goto errout;
+ if (IS_ERR(fp)) {
+ fc_fcp_error(fsp, fp);
+ return;
+ }

fh = fc_frame_header_get(fp);
r_ctl = fh->fh_r_ctl;
@@ -719,11 +740,6 @@ unlock:
fc_fcp_unlock_pkt(fsp);
out:
fc_frame_free(fp);
-errout:
- if (IS_ERR(fp))
- fc_fcp_error(fsp, fp);
- else if (rc == -ENOMEM)
- fc_fcp_reduce_can_queue(lport);
}

/**
@@ -885,7 +901,7 @@ static void fc_fcp_complete_locked(struct fc_fcp_pkt *fsp)
struct fc_seq *csp;

csp = lport->tt.seq_start_next(seq);
- conf_frame = fc_frame_alloc(fsp->lp, 0);
+ conf_frame = fc_fcp_frame_alloc(fsp->lp, 0);
if (conf_frame) {
f_ctl = FC_FC_SEQ_INIT;
f_ctl |= FC_FC_LAST_SEQ | FC_FC_END_SEQ;
@@ -1025,7 +1041,7 @@ static int fc_fcp_cmd_send(struct fc_lport *lport, struct fc_fcp_pkt *fsp,
if (fc_fcp_lock_pkt(fsp))
return 0;

- fp = fc_frame_alloc(lport, sizeof(fsp->cdb_cmd));
+ fp = fc_fcp_frame_alloc(lport, sizeof(fsp->cdb_cmd));
if (!fp) {
rc = -1;
goto unlock;
@@ -1306,7 +1322,7 @@ static void fc_fcp_rec(struct fc_fcp_pkt *fsp)
fc_fcp_complete_locked(fsp);
return;
}
- fp = fc_frame_alloc(lport, sizeof(struct fc_els_rec));
+ fp = fc_fcp_frame_alloc(lport, sizeof(struct fc_els_rec));
if (!fp)
goto retry;

@@ -1558,7 +1574,7 @@ static void fc_fcp_srr(struct fc_fcp_pkt *fsp, enum fc_rctl r_ctl, u32 offset)
if (!(rpriv->flags & FC_RP_FLAGS_RETRY) ||
rpriv->rp_state != RPORT_ST_READY)
goto retry; /* shouldn't happen */
- fp = fc_frame_alloc(lport, sizeof(*srr));
+ fp = fc_fcp_frame_alloc(lport, sizeof(*srr));
if (!fp)
goto retry;