From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 17/21] libata: improve SCSI scan failure handling Date: Mon, 16 Jul 2007 14:29:40 +0900 Message-ID: <11845637801356-git-send-email-htejun@gmail.com> References: <11845637782629-git-send-email-htejun@gmail.com> Reply-To: Tejun Heo Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: Received: from nz-out-0506.google.com ([64.233.162.234]:11862 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761652AbXGPF3x (ORCPT ); Mon, 16 Jul 2007 01:29:53 -0400 Received: by nz-out-0506.google.com with SMTP id s18so736630nze for ; Sun, 15 Jul 2007 22:29:53 -0700 (PDT) In-Reply-To: <11845637782629-git-send-email-htejun@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik , Alan Cox , linux-ide@vger.kernel.org, Forrest Zhao Cc: Tejun Heo SCSI scan may fail due to memory allocation failure even if EH is not in progress. Due to use of GFP_ATOMIC in SCSI scan path, allocation failure isn't too rare especially while probing multiple devices at once which is the case when a bunch of devices are connected to PMP. This patch moves SCSI scan failure detetion logic from ata_scsi_hotplug() to ata_scsi_scan_host() and implement synchronous scan behavior. The synchronous path sleeps briefly and repeats SCSI scan if some devices aren't attached properly. It contains robust retry loop to minimize the chance of device misdetection during boot and falls back to async retry if everything fails. Signed-off-by: Tejun Heo --- drivers/ata/libata-core.c | 2 +- drivers/ata/libata-scsi.c | 63 +++++++++++++++++++++++++++++++++----------- drivers/ata/libata.h | 2 +- 3 files changed, 49 insertions(+), 18 deletions(-) diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 58bc40e..155061e 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -6452,7 +6452,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht) for (i = 0; i < host->n_ports; i++) { struct ata_port *ap = host->ports[i]; - ata_scsi_scan_host(ap); + ata_scsi_scan_host(ap, 1); } return 0; diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index cfde22d..12ac0b5 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -2947,17 +2947,22 @@ int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht) return rc; } -void ata_scsi_scan_host(struct ata_port *ap) +void ata_scsi_scan_host(struct ata_port *ap, int sync) { + int tries = 5; + struct ata_device *last_failed_dev = NULL; + struct ata_device *dev; unsigned int i; if (ap->flags & ATA_FLAG_DISABLED) return; + repeat: for (i = 0; i < ATA_MAX_DEVICES; i++) { - struct ata_device *dev = &ap->device[i]; struct scsi_device *sdev; + dev = &ap->device[i]; + if (!ata_dev_enabled(dev) || dev->sdev) continue; @@ -2967,6 +2972,45 @@ void ata_scsi_scan_host(struct ata_port *ap) scsi_device_put(sdev); } } + + /* If we scanned while EH was in progress or allocation + * failure occurred, scan would have failed silently. Check + * whether all devices are attached. + */ + for (i = 0; i < ATA_MAX_DEVICES; i++) { + dev = &ap->device[i]; + if (ata_dev_enabled(dev) && !dev->sdev) + break; + } + if (i == ATA_MAX_DEVICES) + return; + + /* we're missing some SCSI devices */ + if (sync) { + /* If caller requested synchrnous scan && we've made + * any progress, sleep briefly and repeat. + */ + if (dev != last_failed_dev) { + msleep(100); + last_failed_dev = dev; + goto repeat; + } + + /* We might be failing to detect boot device, give it + * a few more chances. + */ + if (--tries) { + msleep(100); + goto repeat; + } + + ata_port_printk(ap, KERN_ERR, "WARNING: synchronous SCSI scan " + "failed without making any progress,\n" + " switching to async\n"); + } + + queue_delayed_work(ata_aux_wq, &ap->hotplug_task, + round_jiffies_relative(HZ)); } /** @@ -3093,20 +3137,7 @@ void ata_scsi_hotplug(struct work_struct *work) } /* scan for new ones */ - ata_scsi_scan_host(ap); - - /* If we scanned while EH was in progress, scan would have - * failed silently. Requeue if there are enabled but - * unattached devices. - */ - for (i = 0; i < ATA_MAX_DEVICES; i++) { - struct ata_device *dev = &ap->device[i]; - if (ata_dev_enabled(dev) && !dev->sdev) { - queue_delayed_work(ata_aux_wq, &ap->hotplug_task, - round_jiffies_relative(HZ)); - break; - } - } + ata_scsi_scan_host(ap, 0); DPRINTK("EXIT\n"); } diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h index ba17fc5..48836b2 100644 --- a/drivers/ata/libata.h +++ b/drivers/ata/libata.h @@ -112,7 +112,7 @@ static inline int ata_acpi_on_devcfg(struct ata_device *adev) { return 0; } /* libata-scsi.c */ extern int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht); -extern void ata_scsi_scan_host(struct ata_port *ap); +extern void ata_scsi_scan_host(struct ata_port *ap, int sync); extern int ata_scsi_offline_dev(struct ata_device *dev); extern void ata_scsi_hotplug(struct work_struct *work); extern unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf, -- 1.5.0.3