From patchwork Tue Feb 25 06:23:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Gilbert X-Patchwork-Id: 11402545 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4E31B92A for ; Tue, 25 Feb 2020 06:24:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F5DD2176D for ; Tue, 25 Feb 2020 06:24:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729068AbgBYGYD (ORCPT ); Tue, 25 Feb 2020 01:24:03 -0500 Received: from smtp.infotech.no ([82.134.31.41]:36077 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725783AbgBYGYC (ORCPT ); Tue, 25 Feb 2020 01:24:02 -0500 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id F34CF20425A; Tue, 25 Feb 2020 07:23:59 +0100 (CET) X-Virus-Scanned: by amavisd-new-2.6.6 (20110518) (Debian) at infotech.no Received: from smtp.infotech.no ([127.0.0.1]) by localhost (smtp.infotech.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id c9h4Q2El9MTh; Tue, 25 Feb 2020 07:23:57 +0100 (CET) Received: from xtwo70.bingwo.ca (host-23-251-188-50.dyn.295.ca [23.251.188.50]) by smtp.infotech.no (Postfix) with ESMTPA id F25A22041E3; Tue, 25 Feb 2020 07:23:56 +0100 (CET) From: Douglas Gilbert To: linux-scsi@vger.kernel.org Cc: martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, hare@suse.de, Damien.LeMoal@wdc.com Subject: [PATCH v4 01/14] scsi_debug: randomize command completion time Date: Tue, 25 Feb 2020 01:23:38 -0500 Message-Id: <20200225062351.21267-2-dgilbert@interlog.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200225062351.21267-1-dgilbert@interlog.com> References: <20200225062351.21267-1-dgilbert@interlog.com> MIME-Version: 1.0 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Add a new command line option (e.g. random=1) and sysfs attribute that causes subsequent command completion times to be between the current command delay setting and 0. A unformily distributed 32 bit, kernel provided integer is used for this purpose. Since the existing 'delay' whose units are jiffies (typically milliseconds) and 'ndelay' (units: nanoseconds) options (and sysfs attributes) span a range greater than 32 bits, some scaling is required. The purpose of this patch is to widen the range of testing cases that are visited in long running tests. Put simply: rarely struct race conditions are more likely to be found when this facility is used. The default is the previous case in which all command completions were roughly equal to (if not, slightly longer) than the value given by the 'delay' or 'ndelay' settings (or their defaults). This option's default is equivalent to setting 'random=0' . Reviewed-by: Hannes Reinecke Signed-off-by: Douglas Gilbert --- drivers/scsi/scsi_debug.c | 42 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c index 44cb054d5e66..18c07e9ace15 100644 --- a/drivers/scsi/scsi_debug.c +++ b/drivers/scsi/scsi_debug.c @@ -38,6 +38,7 @@ #include #include #include +#include #include @@ -125,6 +126,7 @@ static const char *sdebug_version_date = "20190125"; #define DEF_PHYSBLK_EXP 0 #define DEF_OPT_XFERLEN_EXP 0 #define DEF_PTYPE TYPE_DISK +#define DEF_RANDOM false #define DEF_REMOVABLE false #define DEF_SCSI_LEVEL 7 /* INQUIRY, byte2 [6->SPC-4; 7->SPC-5] */ #define DEF_SECTOR_SIZE 512 @@ -655,6 +657,7 @@ static unsigned int sdebug_unmap_max_blocks = DEF_UNMAP_MAX_BLOCKS; static unsigned int sdebug_unmap_max_desc = DEF_UNMAP_MAX_DESC; static unsigned int sdebug_write_same_length = DEF_WRITESAME_LENGTH; static int sdebug_uuid_ctl = DEF_UUID_CTL; +static bool sdebug_random = DEF_RANDOM; static bool sdebug_removable = DEF_REMOVABLE; static bool sdebug_clustering; static bool sdebug_host_lock = DEF_HOST_LOCK; @@ -4354,9 +4357,21 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip, ktime_t kt; if (delta_jiff > 0) { - kt = ns_to_ktime((u64)delta_jiff * (NSEC_PER_SEC / HZ)); - } else - kt = ndelay; + u64 ns = jiffies_to_nsecs(delta_jiff); + + if (sdebug_random && ns < U32_MAX) { + ns = prandom_u32_max((u32)ns); + } else if (sdebug_random) { + ns >>= 12; /* scale to 4 usec precision */ + if (ns < U32_MAX) /* over 4 hours max */ + ns = prandom_u32_max((u32)ns); + ns <<= 12; + } + kt = ns_to_ktime(ns); + } else { /* ndelay has a 4.2 second max */ + kt = sdebug_random ? prandom_u32_max((u32)ndelay) : + (u32)ndelay; + } if (!sd_dp->init_hrt) { sd_dp->init_hrt = true; sqcp->sd_dp = sd_dp; @@ -4451,6 +4466,7 @@ module_param_named(opts, sdebug_opts, int, S_IRUGO | S_IWUSR); module_param_named(physblk_exp, sdebug_physblk_exp, int, S_IRUGO); module_param_named(opt_xferlen_exp, sdebug_opt_xferlen_exp, int, S_IRUGO); module_param_named(ptype, sdebug_ptype, int, S_IRUGO | S_IWUSR); +module_param_named(random, sdebug_random, bool, S_IRUGO | S_IWUSR); module_param_named(removable, sdebug_removable, bool, S_IRUGO | S_IWUSR); module_param_named(scsi_level, sdebug_scsi_level, int, S_IRUGO); module_param_named(sector_size, sdebug_sector_size, int, S_IRUGO); @@ -4511,6 +4527,7 @@ MODULE_PARM_DESC(opts, "1->noise, 2->medium_err, 4->timeout, 8->recovered_err... MODULE_PARM_DESC(physblk_exp, "physical block exponent (def=0)"); MODULE_PARM_DESC(opt_xferlen_exp, "optimal transfer length granularity exponent (def=physblk_exp)"); MODULE_PARM_DESC(ptype, "SCSI peripheral type(def=0[disk])"); +MODULE_PARM_DESC(random, "If set, uniformly randomize command duration between 0 and delay_in_ns"); MODULE_PARM_DESC(removable, "claim to have removable media (def=0)"); MODULE_PARM_DESC(scsi_level, "SCSI level to simulate(def=7[SPC-5])"); MODULE_PARM_DESC(sector_size, "logical block size in bytes (def=512)"); @@ -5101,6 +5118,24 @@ static ssize_t map_show(struct device_driver *ddp, char *buf) } static DRIVER_ATTR_RO(map); +static ssize_t random_show(struct device_driver *ddp, char *buf) +{ + return scnprintf(buf, PAGE_SIZE, "%d\n", (int)sdebug_random); +} + +static ssize_t random_store(struct device_driver *ddp, const char *buf, + size_t count) +{ + int n; + + if (count > 0 && kstrtoint(buf, 10, &n) == 0 && n >= 0) { + sdebug_random = (n > 0); + return count; + } + return -EINVAL; +} +static DRIVER_ATTR_RW(random); + static ssize_t removable_show(struct device_driver *ddp, char *buf) { return scnprintf(buf, PAGE_SIZE, "%d\n", sdebug_removable ? 1 : 0); @@ -5211,6 +5246,7 @@ static struct attribute *sdebug_drv_attrs[] = { &driver_attr_guard.attr, &driver_attr_ato.attr, &driver_attr_map.attr, + &driver_attr_random.attr, &driver_attr_removable.attr, &driver_attr_host_lock.attr, &driver_attr_ndelay.attr,