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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Steffen Maier <maier@linux.ibm.com>,
	Benjamin Block <bblock@linux.ibm.com>,
	Jens Remus <jremus@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	"Sasha Levin (Microsoft)" <sashal@kernel.org>
Subject: [PATCH 4.9 27/32] scsi: zfcp: reduce flood of fcrscn1 trace records on multi-element RSCN
Date: Thu,  2 May 2019 17:21:13 +0200	[thread overview]
Message-ID: <20190502143322.130184791@linuxfoundation.org> (raw)
In-Reply-To: <20190502143314.649935114@linuxfoundation.org>

[ Upstream commit c8206579175c34a2546de8a74262456278a7795a ]

If an incoming ELS of type RSCN contains more than one element, zfcp
suboptimally causes repeated erp trigger NOP trace records for each
previously failed port. These could be ports that went away.  It loops over
each RSCN element, and for each of those in an inner loop over all
zfcp_ports.

The trigger to recover failed ports should be just the reception of some
RSCN, no matter how many elements it has. So we can loop over failed ports
separately, and only then loop over each RSCN element to handle the
non-failed ports.

The call chain was:

  zfcp_fc_incoming_rscn
    for (i = 1; i < no_entries; i++)
      _zfcp_fc_incoming_rscn
        list_for_each_entry(port, &adapter->port_list, list)
          if (masked port->d_id match) zfcp_fc_test_link
          if (!port->d_id) zfcp_erp_port_reopen "fcrscn1"   <===

In order the reduce the "flooding" of the REC trace area in such cases, we
factor out handling the failed ports to be outside of the entries loop:

  zfcp_fc_incoming_rscn
    if (no_entries > 1)                                     <===
      list_for_each_entry(port, &adapter->port_list, list)  <===
        if (!port->d_id) zfcp_erp_port_reopen "fcrscn1"     <===
    for (i = 1; i < no_entries; i++)
      _zfcp_fc_incoming_rscn
        list_for_each_entry(port, &adapter->port_list, list)
          if (masked port->d_id match) zfcp_fc_test_link

Abbreviated example trace records before this code change:

Tag            : fcrscn1
WWPN           : 0x500507630310d327
ERP want       : 0x02
ERP need       : 0x02

Tag            : fcrscn1
WWPN           : 0x500507630310d327
ERP want       : 0x02
ERP need       : 0x00                 NOP => superfluous trace record

The last trace entry repeats if there are more than 2 RSCN elements.

Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
---
 drivers/s390/scsi/zfcp_fc.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index 237688af179b..f7630cf581cd 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -238,10 +238,6 @@ static void _zfcp_fc_incoming_rscn(struct zfcp_fsf_req *fsf_req, u32 range,
 	list_for_each_entry(port, &adapter->port_list, list) {
 		if ((port->d_id & range) == (ntoh24(page->rscn_fid) & range))
 			zfcp_fc_test_link(port);
-		if (!port->d_id)
-			zfcp_erp_port_reopen(port,
-					     ZFCP_STATUS_COMMON_ERP_FAILED,
-					     "fcrscn1");
 	}
 	read_unlock_irqrestore(&adapter->port_list_lock, flags);
 }
@@ -249,6 +245,7 @@ static void _zfcp_fc_incoming_rscn(struct zfcp_fsf_req *fsf_req, u32 range,
 static void zfcp_fc_incoming_rscn(struct zfcp_fsf_req *fsf_req)
 {
 	struct fsf_status_read_buffer *status_buffer = (void *)fsf_req->data;
+	struct zfcp_adapter *adapter = fsf_req->adapter;
 	struct fc_els_rscn *head;
 	struct fc_els_rscn_page *page;
 	u16 i;
@@ -261,6 +258,22 @@ static void zfcp_fc_incoming_rscn(struct zfcp_fsf_req *fsf_req)
 	/* see FC-FS */
 	no_entries = head->rscn_plen / sizeof(struct fc_els_rscn_page);
 
+	if (no_entries > 1) {
+		/* handle failed ports */
+		unsigned long flags;
+		struct zfcp_port *port;
+
+		read_lock_irqsave(&adapter->port_list_lock, flags);
+		list_for_each_entry(port, &adapter->port_list, list) {
+			if (port->d_id)
+				continue;
+			zfcp_erp_port_reopen(port,
+					     ZFCP_STATUS_COMMON_ERP_FAILED,
+					     "fcrscn1");
+		}
+		read_unlock_irqrestore(&adapter->port_list_lock, flags);
+	}
+
 	for (i = 1; i < no_entries; i++) {
 		/* skip head and start with 1st element */
 		page++;
-- 
2.19.1




  parent reply	other threads:[~2019-05-02 15:22 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-02 15:20 [PATCH 4.9 00/32] 4.9.173-stable review Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 01/32] usbnet: ipheth: prevent TX queue timeouts when device not ready Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 02/32] usbnet: ipheth: fix potential null pointer dereference in ipheth_carrier_set Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 03/32] media: vivid: check if the cec_adapter is valid Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 04/32] ARM: dts: bcm283x: Fix hdmi hpd gpio pull Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 05/32] s390: limit brk randomization to 32MB Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 06/32] qlcnic: Avoid potential NULL pointer dereference Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 07/32] netfilter: nft_set_rbtree: check for inactive element after flag mismatch Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 08/32] netfilter: bridge: set skb transport_header before entering NF_INET_PRE_ROUTING Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 09/32] sc16is7xx: missing unregister/delete driver on error in sc16is7xx_init() Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 10/32] serial: ar933x_uart: Fix build failure with disabled console Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 11/32] usb: gadget: net2280: Fix overrun of OUT messages Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 12/32] usb: gadget: net2280: Fix net2280_dequeue() Greg Kroah-Hartman
2019-05-02 15:20 ` [PATCH 4.9 13/32] usb: gadget: net2272: Fix net2272_dequeue() Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 14/32] ARM: dts: pfla02: increase phy reset duration Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 15/32] net: ks8851: Dequeue RX packets explicitly Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 16/32] net: ks8851: Reassert reset pin if chip ID check fails Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 17/32] net: ks8851: Delay requesting IRQ until opened Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 18/32] net: ks8851: Set initial carrier state to down Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 19/32] staging: rtl8712: uninitialized memory in read_bbreg_hdl() Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 20/32] NFS: Fix a typo in nfs_init_timeout_values() Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 21/32] net: xilinx: fix possible object reference leak Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 22/32] net: ibm: " Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 23/32] net: ethernet: ti: " Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 24/32] scsi: qla4xxx: fix a potential NULL pointer dereference Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 25/32] usb: u132-hcd: fix resource leak Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 26/32] ceph: fix use-after-free on symlink traversal Greg Kroah-Hartman
2019-05-02 15:21 ` Greg Kroah-Hartman [this message]
2019-05-02 15:21 ` [PATCH 4.9 28/32] libata: fix using DMA buffers on stack Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 29/32] gpio: of: Fix of_gpiochip_add() error path Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 30/32] kconfig/[mn]conf: handle backspace (^H) key Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 31/32] leds: pca9532: fix a potential NULL pointer dereference Greg Kroah-Hartman
2019-05-02 15:21 ` [PATCH 4.9 32/32] vfio/type1: Limit DMA mappings per container Greg Kroah-Hartman
2019-05-02 23:06 ` [PATCH 4.9 00/32] 4.9.173-stable review kernelci.org bot
2019-05-03  7:04 ` Naresh Kamboju
2019-05-03  9:27 ` Jon Hunter
2019-05-03 17:15 ` Guenter Roeck
2019-05-03 21:21 ` shuah

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