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Subject[PATCH 3/3] scsi/fcoe: Add a local_lock to percpu localport statistics
Date
Updating the per-CPU lport->stats relies on disabling preemption
with get/put_cpu() semantics. However, this is a bit harsh for
PREEMPT_RT and by using a local_lock, it can allow the region
to be preemptible, guaranteeing CPU locality, without making any
difference to the non-RT common case as it will continue to
disable preemption.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 16 ++++++++++------
drivers/scsi/bnx2fc/bnx2fc_io.c | 5 +++--
drivers/scsi/fcoe/fcoe.c | 29 ++++++++++++++++++-----------
drivers/scsi/fcoe/fcoe_ctlr.c | 24 +++++++++++++++---------
drivers/scsi/libfc/fc_fcp.c | 31 ++++++++++++++++++++++---------
drivers/scsi/qedf/qedf_main.c | 7 ++++---
include/scsi/libfc.h | 7 +++++++
7 files changed, 79 insertions(+), 40 deletions(-)

diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
index 71fa62bd3083..25bb08514824 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
@@ -398,11 +398,12 @@ static int bnx2fc_xmit(struct fc_lport *lport, struct fc_frame *fp)
skb_shinfo(skb)->gso_size = 0;
}

- /*update tx stats */
- stats = per_cpu_ptr(lport->stats, get_cpu());
+ /* update tx stats */
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
stats->TxFrames++;
stats->TxWords += wlen;
- put_cpu();
+ local_unlock(&lport->stats->lock);

/* send down to lld */
fr_dev(fp) = lport;
@@ -870,6 +871,7 @@ static void bnx2fc_indicate_netevent(void *context, unsigned long event,
struct fc_lport *vport;
struct bnx2fc_interface *interface, *tmp;
struct fcoe_ctlr *ctlr;
+ struct fc_stats *stats;
int wait_for_upload = 0;
u32 link_possible = 1;

@@ -962,9 +964,11 @@ static void bnx2fc_indicate_netevent(void *context, unsigned long event,
mutex_unlock(&lport->lp_mutex);
fc_host_port_type(lport->host) =
FC_PORTTYPE_UNKNOWN;
- per_cpu_ptr(lport->stats,
- get_cpu())->LinkFailureCount++;
- put_cpu();
+
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
+ stats->LinkFailureCount++;
+ local_unlock(&lport->stats->lock);
fcoe_clean_pending_queue(lport);
wait_for_upload = 1;
}
diff --git a/drivers/scsi/bnx2fc/bnx2fc_io.c b/drivers/scsi/bnx2fc/bnx2fc_io.c
index b9114113ee73..219ce4bc4008 100644
--- a/drivers/scsi/bnx2fc/bnx2fc_io.c
+++ b/drivers/scsi/bnx2fc/bnx2fc_io.c
@@ -2046,7 +2046,8 @@ int bnx2fc_post_io_req(struct bnx2fc_rport *tgt,
io_req->data_xfer_len = scsi_bufflen(sc_cmd);
sc_cmd->SCp.ptr = (char *)io_req;

- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
if (sc_cmd->sc_data_direction == DMA_FROM_DEVICE) {
io_req->io_req_flags = BNX2FC_READ;
stats->InputRequests++;
@@ -2059,7 +2060,7 @@ int bnx2fc_post_io_req(struct bnx2fc_rport *tgt,
io_req->io_req_flags = 0;
stats->ControlRequests++;
}
- put_cpu();
+ local_unlock(&lport->stats->lock);

xid = io_req->xid;

diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index a0064a1b4a32..80e6d5427d51 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -1339,6 +1339,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
struct fcoe_interface *fcoe;
struct fc_frame_header *fh;
struct fcoe_percpu_s *fps;
+ struct fc_stats *stats;
struct ethhdr *eh;
unsigned int cpu;

@@ -1433,8 +1434,10 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,

return NET_RX_SUCCESS;
err:
- per_cpu_ptr(lport->stats, get_cpu())->ErrorFrames++;
- put_cpu();
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
+ stats->ErrorFrames++;
+ local_unlock(&lport->stats->lock);
err2:
kfree_skb(skb);
return NET_RX_DROP;
@@ -1585,10 +1588,11 @@ static int fcoe_xmit(struct fc_lport *lport, struct fc_frame *fp)
skb_shinfo(skb)->gso_size = 0;
}
/* update tx stats: regardless if LLD fails */
- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
stats->TxFrames++;
stats->TxWords += wlen;
- put_cpu();
+ local_unlock(&lport->stats->lock);

/* send down to lld */
fr_dev(fp) = lport;
@@ -1640,11 +1644,12 @@ static inline int fcoe_filter_frames(struct fc_lport *lport,
return 0;
}

- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
stats->InvalidCRCCount++;
if (stats->InvalidCRCCount < 5)
printk(KERN_WARNING "fcoe: dropping frame with CRC error\n");
- put_cpu();
+ local_unlock(&lport->stats->lock);
return -EINVAL;
}

@@ -1685,7 +1690,8 @@ static void fcoe_recv_frame(struct sk_buff *skb)
*/
hp = (struct fcoe_hdr *) skb_network_header(skb);

- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
if (unlikely(FC_FCOE_DECAPS_VER(hp) != FC_FCOE_VER)) {
if (stats->ErrorFrames < 5)
printk(KERN_WARNING "fcoe: FCoE version "
@@ -1717,13 +1723,13 @@ static void fcoe_recv_frame(struct sk_buff *skb)
goto drop;

if (!fcoe_filter_frames(lport, fp)) {
- put_cpu();
+ local_unlock(&lport->stats->lock);
fc_exch_recv(lport, fp);
return;
}
drop:
stats->ErrorFrames++;
- put_cpu();
+ local_unlock(&lport->stats->lock);
kfree_skb(skb);
}

@@ -1921,9 +1927,10 @@ static int fcoe_device_notification(struct notifier_block *notifier,
break;
case FCOE_CTLR_ENABLED:
case FCOE_CTLR_UNUSED:
- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
stats->LinkFailureCount++;
- put_cpu();
+ local_unlock(&lport->stats->lock);
fcoe_clean_pending_queue(lport);
}
}
diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
index 1756a0ac6f08..d033aacafc5e 100644
--- a/drivers/scsi/fcoe/fcoe_ctlr.c
+++ b/drivers/scsi/fcoe/fcoe_ctlr.c
@@ -828,7 +828,8 @@ static unsigned long fcoe_ctlr_age_fcfs(struct fcoe_ctlr *fip)

INIT_LIST_HEAD(&del_list);

- stats = per_cpu_ptr(fip->lp->stats, get_cpu());
+ local_lock(&fip->lp->stats->lock);
+ stats = this_cpu_ptr(fip->lp->stats);

list_for_each_entry_safe(fcf, next, &fip->fcfs, list) {
deadline = fcf->time + fcf->fka_period + fcf->fka_period / 2;
@@ -864,7 +865,7 @@ static unsigned long fcoe_ctlr_age_fcfs(struct fcoe_ctlr *fip)
sel_time = fcf->time;
}
}
- put_cpu();
+ local_unlock(&fip->lp->stats->lock);

list_for_each_entry_safe(fcf, next, &del_list, list) {
/* Removes fcf from current list */
@@ -1286,10 +1287,11 @@ static void fcoe_ctlr_recv_els(struct fcoe_ctlr *fip, struct sk_buff *skb)
fr_dev(fp) = lport;
fr_encaps(fp) = els_dtype;

- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
stats->RxFrames++;
stats->RxWords += skb->len / FIP_BPW;
- put_cpu();
+ local_unlock(&lport->stats->lock);

fc_exch_recv(lport, fp);
return;
@@ -1321,6 +1323,7 @@ static void fcoe_ctlr_recv_clr_vlink(struct fcoe_ctlr *fip,
struct fcoe_fcf *fcf = fip->sel_fcf;
struct fc_lport *lport = fip->lp;
struct fc_lport *vn_port = NULL;
+ struct fc_stats *stats;
u32 desc_mask;
int num_vlink_desc;
int reset_phys_port = 0;
@@ -1427,9 +1430,10 @@ static void fcoe_ctlr_recv_clr_vlink(struct fcoe_ctlr *fip,
ntoh24(vp->fd_fc_id));
if (vn_port && (vn_port == lport)) {
mutex_lock(&fip->ctlr_mutex);
- per_cpu_ptr(lport->stats,
- get_cpu())->VLinkFailureCount++;
- put_cpu();
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
+ stats->VLinkFailureCount++;
+ local_unlock(&lport->stats->lock);
fcoe_ctlr_reset(fip);
mutex_unlock(&fip->ctlr_mutex);
}
@@ -1457,8 +1461,10 @@ static void fcoe_ctlr_recv_clr_vlink(struct fcoe_ctlr *fip,
* followed by physical port
*/
mutex_lock(&fip->ctlr_mutex);
- per_cpu_ptr(lport->stats, get_cpu())->VLinkFailureCount++;
- put_cpu();
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
+ stats->VLinkFailureCount++;
+ local_unlock(&lport->stats->lock);
fcoe_ctlr_reset(fip);
mutex_unlock(&fip->ctlr_mutex);

diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
index 871b11edb586..bee26f4f2ea6 100644
--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -147,8 +147,12 @@ static struct fc_fcp_pkt *fc_fcp_pkt_alloc(struct fc_lport *lport, gfp_t gfp)
INIT_LIST_HEAD(&fsp->list);
spin_lock_init(&fsp->scsi_pkt_lock);
} else {
- per_cpu_ptr(lport->stats, get_cpu())->FcpPktAllocFails++;
- put_cpu();
+ struct fc_stats *stats;
+
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
+ stats->FcpPktAllocFails++;
+ local_unlock(&lport->stats->lock);
}
return fsp;
}
@@ -266,12 +270,15 @@ static void fc_fcp_abort_done(struct fc_fcp_pkt *fsp)
static int fc_fcp_send_abort(struct fc_fcp_pkt *fsp)
{
int rc;
+ struct fc_stats *stats;

if (!fsp->seq_ptr)
return -EINVAL;

- per_cpu_ptr(fsp->lp->stats, get_cpu())->FcpPktAborts++;
- put_cpu();
+ local_lock(&fsp->lp->stats->lock);
+ stats = this_cpu_ptr(fsp->lp->stats);
+ stats->FcpPktAborts++;
+ local_unlock(&fsp->lp->stats->lock);

fsp->state |= FC_SRB_ABORT_PENDING;
rc = fc_seq_exch_abort(fsp->seq_ptr, 0);
@@ -435,13 +442,16 @@ static inline struct fc_frame *fc_fcp_frame_alloc(struct fc_lport *lport,
size_t len)
{
struct fc_frame *fp;
+ struct fc_stats *stats;

fp = fc_frame_alloc(lport, len);
if (likely(fp))
return fp;

- per_cpu_ptr(lport->stats, get_cpu())->FcpFrameAllocFails++;
- put_cpu();
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
+ stats->FcpFrameAllocFails++;
+ local_unlock(&lport->stats->lock);
/* error case */
fc_fcp_can_queue_ramp_down(lport);
shost_printk(KERN_ERR, lport->host,
@@ -537,8 +547,10 @@ static void fc_fcp_recv_data(struct fc_fcp_pkt *fsp, struct fc_frame *fp)

if (~crc != le32_to_cpu(fr_crc(fp))) {
crc_err:
- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
stats->ErrorFrames++;
+ local_unlock(&lport->stats->lock);
/* per cpu count, not total count, but OK for limit */
if (stats->InvalidCRCCount++ < FC_MAX_ERROR_CNT)
printk(KERN_WARNING "libfc: CRC error on data "
@@ -1917,7 +1929,8 @@ int fc_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *sc_cmd)
/*
* setup the data direction
*/
- stats = per_cpu_ptr(lport->stats, get_cpu());
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
if (sc_cmd->sc_data_direction == DMA_FROM_DEVICE) {
fsp->req_flags = FC_SRB_READ;
stats->InputRequests++;
@@ -1930,7 +1943,7 @@ int fc_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *sc_cmd)
fsp->req_flags = 0;
stats->ControlRequests++;
}
- put_cpu();
+ local_unlock(&lport->stats->lock);

/*
* send it to the lower layer
diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
index 1bf7a22d4948..1488f7431db5 100644
--- a/drivers/scsi/qedf/qedf_main.c
+++ b/drivers/scsi/qedf/qedf_main.c
@@ -1213,11 +1213,12 @@ static int qedf_xmit(struct fc_lport *lport, struct fc_frame *fp)
FC_FCOE_ENCAPS_VER(hp, FC_FCOE_VER);
hp->fcoe_sof = sof;

- /*update tx stats */
- stats = per_cpu_ptr(lport->stats, get_cpu());
+ /* update tx stats */
+ local_lock(&lport->stats->lock);
+ stats = this_cpu_ptr(lport->stats);
stats->TxFrames++;
stats->TxWords += wlen;
- put_cpu();
+ local_unlock(&lport->stats->lock);

/* Get VLAN ID from skb for printing purposes */
__vlan_hwaccel_get_tag(skb, &vlan_tci);
diff --git a/include/scsi/libfc.h b/include/scsi/libfc.h
index eeb8d689ff6b..d8d717bdbb74 100644
--- a/include/scsi/libfc.h
+++ b/include/scsi/libfc.h
@@ -240,6 +240,7 @@ struct fc_rport_priv {
* @OutputBytes: Number of transmitted bytes
* @VLinkFailureCount: Number of virtual link failures
* @MissDiscAdvCount: Number of missing FIP discovery advertisement
+ * @lock: Protects percpu stats management
*/
struct fc_stats {
u64 SecondsSinceLastReset;
@@ -263,6 +264,7 @@ struct fc_stats {
u64 OutputBytes;
u64 VLinkFailureCount;
u64 MissDiscAdvCount;
+ local_lock_t lock;
};

/**
@@ -824,9 +826,14 @@ static inline void fc_lport_state_enter(struct fc_lport *lport,
*/
static inline int fc_lport_init_stats(struct fc_lport *lport)
{
+ int cpu;
+
lport->stats = alloc_percpu(struct fc_stats);
if (!lport->stats)
return -ENOMEM;
+
+ for_each_possible_cpu(cpu)
+ local_lock_init(&per_cpu_ptr(lport->stats, cpu)->lock);
return 0;
}

--
2.26.2
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