From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60BA5C6FD18 for ; Tue, 28 Mar 2023 23:39:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229776AbjC1XjJ (ORCPT ); Tue, 28 Mar 2023 19:39:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229470AbjC1XjI (ORCPT ); Tue, 28 Mar 2023 19:39:08 -0400 Received: from mp-relay-02.fibernetics.ca (mp-relay-02.fibernetics.ca [208.85.217.137]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40CE81FDB; Tue, 28 Mar 2023 16:39:07 -0700 (PDT) Received: from mailpool-fe-02.fibernetics.ca (mailpool-fe-02.fibernetics.ca [208.85.217.145]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mp-relay-02.fibernetics.ca (Postfix) with ESMTPS id 9E766764DB; Tue, 28 Mar 2023 23:39:06 +0000 (UTC) Received: from localhost (mailpool-mx-01.fibernetics.ca [208.85.217.140]) by mailpool-fe-02.fibernetics.ca (Postfix) with ESMTP id 8CACF60BE9; Tue, 28 Mar 2023 23:39:06 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at Received: from mailpool-fe-02.fibernetics.ca ([208.85.217.145]) by localhost (mail-mx-01.fibernetics.ca [208.85.217.140]) (amavisd-new, port 10024) with ESMTP id B8jxcH6ZGlUY; Tue, 28 Mar 2023 23:39:06 +0000 (UTC) Received: from [192.168.48.17] (host-184-164-23-94.dyn.295.ca [184.164.23.94]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) (Authenticated sender: dgilbert@interlog.com) by mail.ca.inter.net (Postfix) with ESMTPSA id ED92960BE8; Tue, 28 Mar 2023 23:39:05 +0000 (UTC) Message-ID: <2651d29d-3aa8-065c-4c94-102bd20932b4@interlog.com> Date: Tue, 28 Mar 2023 19:39:05 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Reply-To: dgilbert@interlog.com Subject: Re: [PATCH v3 02/11] scsi: scsi_debug: Don't iter all shosts in clear_luns_changed_on_target() Content-Language: en-CA To: John Garry , jejb@linux.ibm.com, martin.petersen@oracle.com Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, bvanassche@acm.org References: <20230327074310.1862889-1-john.g.garry@oracle.com> <20230327074310.1862889-3-john.g.garry@oracle.com> From: Douglas Gilbert In-Reply-To: <20230327074310.1862889-3-john.g.garry@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2023-03-27 03:43, John Garry wrote: > In clear_luns_changed_on_target(), we iter all devices for all shosts to > conditionally clear the SDEBUG_UA_LUNS_CHANGED flag in the per-device > uas_bm. > > One condition to see whether we clear the flag is to test whether the host > for the device under consideration is the same as the matching device's > (devip) host. This check will only ever pass for devices for the same > shost, so only iter the devices for the matching device shost. > > We can now drop the spinlock'ing of the sdebug_host_list_lock in the same > function. This will allow us to use a mutex instead of the spinlock for > the global shost lock, as clear_luns_changed_on_target() could be called > in non-blocking context, in scsi_debug_queuecommand() -> make_ua() -> > clear_luns_changed_on_target() (which is why required a spinlock). > > Signed-off-by: John Garry Acked-by: Douglas Gilbert --- > drivers/scsi/scsi_debug.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c > index 782515abca2c..eba6eca81e84 100644 > --- a/drivers/scsi/scsi_debug.c > +++ b/drivers/scsi/scsi_debug.c > @@ -1063,18 +1063,15 @@ static void all_config_cdb_len(void) > > static void clear_luns_changed_on_target(struct sdebug_dev_info *devip) > { > - struct sdebug_host_info *sdhp; > + struct sdebug_host_info *sdhp = devip->sdbg_host; > struct sdebug_dev_info *dp; > > - spin_lock(&sdebug_host_list_lock); > - list_for_each_entry(sdhp, &sdebug_host_list, host_list) { > - list_for_each_entry(dp, &sdhp->dev_info_list, dev_list) { > - if ((devip->sdbg_host == dp->sdbg_host) && > - (devip->target == dp->target)) > - clear_bit(SDEBUG_UA_LUNS_CHANGED, dp->uas_bm); > + list_for_each_entry(dp, &sdhp->dev_info_list, dev_list) { > + if ((devip->sdbg_host == dp->sdbg_host) && > + (devip->target == dp->target)) { > + clear_bit(SDEBUG_UA_LUNS_CHANGED, dp->uas_bm); > } > } > - spin_unlock(&sdebug_host_list_lock); > } > > static int make_ua(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)