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 43D59CDB47E for ; Thu, 19 Oct 2023 00:24:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229697AbjJSAYK (ORCPT ); Wed, 18 Oct 2023 20:24:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229632AbjJSAYJ (ORCPT ); Wed, 18 Oct 2023 20:24:09 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FEF3FA; Wed, 18 Oct 2023 17:24:08 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0135C433C8; Thu, 19 Oct 2023 00:24:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697675047; bh=qSt752qo9f/9keT34nl3gZ57QzTJAE9kUJGDmOTuT6A=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=P9rHbYMgS6Ebeq77OeQplfox6NKNplO4buyZ2u2TYBozLdO7himqGRDpE2OHFz92d q/ppkTl724FTp0GkpyvJ2mMHLh6ioQV8ZKlRaNVziMUEkv/zzgfkvY0lXZwRb49M5N 0s14TQHRfBDtLQMoELDI3J4b1iAFDJnbkM3IjX8jt0YRrbD7BuGTsfw+WVj7ViJpZP CuATYVTs3bcp+dhYyYpNjf1bF+eJaE4GIoY8J177map+se4bHwXrGunwYd5ozp1loR 8gzuK5/KBDXFxpXnhtWsM8+5/8IN2NdmXHNrLoCBBy0EZtz8hPgZuvQSg53DB/k6mz +o1FJMBVSq2WA== Message-ID: <9ee7edc0-5edb-4e17-abae-bb7ffcf0f147@kernel.org> Date: Thu, 19 Oct 2023 09:24:05 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v13 05/18] scsi: core: Introduce a mechanism for reordering requests in the error handler Content-Language: en-US To: Bart Van Assche , Jens Axboe Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, "Martin K . Petersen" , Christoph Hellwig , Ming Lei , "James E.J. Bottomley" References: <20231018175602.2148415-1-bvanassche@acm.org> <20231018175602.2148415-6-bvanassche@acm.org> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <20231018175602.2148415-6-bvanassche@acm.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 10/19/23 02:54, Bart Van Assche wrote: > Introduce the .eh_needs_prepare_resubmit and the .eh_prepare_resubmit > function pointers in struct scsi_driver. Make the error handler call > .eh_prepare_resubmit() before resubmitting commands if any of the > .eh_needs_prepare_resubmit() invocations return true. A later patch > will use this functionality to sort SCSI commands by LBA from inside > the SCSI disk driver before these are resubmitted by the error handler. > > Cc: Martin K. Petersen > Cc: Damien Le Moal > Cc: Christoph Hellwig > Cc: Ming Lei > Signed-off-by: Bart Van Assche > --- > drivers/scsi/scsi_error.c | 72 ++++++++++++++++++++++++++++++++++++++ > drivers/scsi/scsi_priv.h | 1 + > include/scsi/scsi_driver.h | 2 ++ > 3 files changed, 75 insertions(+) > > diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c > index c67cdcdc3ba8..c877db23a72d 100644 > --- a/drivers/scsi/scsi_error.c > +++ b/drivers/scsi/scsi_error.c > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -2186,6 +2187,75 @@ void scsi_eh_ready_devs(struct Scsi_Host *shost, > } > EXPORT_SYMBOL_GPL(scsi_eh_ready_devs); > > +/* > + * Returns true if .eh_prepare_resubmit should be called for the commands in > + * @done_q. > + */ > +static bool scsi_needs_preparation(struct list_head *done_q) > +{ > + struct scsi_cmnd *scmd; > + > + list_for_each_entry(scmd, done_q, eh_entry) { > + struct scsi_driver *uld; > + bool (*npr)(struct scsi_cmnd *scmd); > + > + if (!scmd->device) > + continue; > + uld = scsi_cmd_to_driver(scmd); > + if (!uld) > + continue; > + npr = uld->eh_needs_prepare_resubmit; > + if (npr && npr(scmd)) > + return true; > + } > + > + return false; > +} > + > +/* > + * Comparison function that allows to sort SCSI commands by ULD driver. > + */ > +static int scsi_cmp_uld(void *priv, const struct list_head *_a, > + const struct list_head *_b) > +{ > + struct scsi_cmnd *a = list_entry(_a, typeof(*a), eh_entry); > + struct scsi_cmnd *b = list_entry(_b, typeof(*b), eh_entry); > + > + /* See also the comment above the list_sort() definition. */ > + return scsi_cmd_to_driver(a) > scsi_cmd_to_driver(b); > +} > + > +void scsi_call_prepare_resubmit(struct list_head *done_q) > +{ > + struct scsi_cmnd *scmd, *next; > + > + if (!scsi_needs_preparation(done_q)) > + return; This function will always go through the list of commands in done_q. That could hurt performance for scsi hosts that do not need this prepare resubmit, which I think is UFS only for now. So can't we just add a flag or something to avoid that ? > + > + /* Sort pending SCSI commands by ULD. */ > + list_sort(NULL, done_q, scsi_cmp_uld); > + > + /* > + * Call .eh_prepare_resubmit for each range of commands with identical > + * ULD driver pointer. > + */ > + list_for_each_entry_safe(scmd, next, done_q, eh_entry) { > + struct scsi_driver *uld = > + scmd->device ? scsi_cmd_to_driver(scmd) : NULL; > + struct list_head *prev, uld_cmd_list; > + > + while (&next->eh_entry != done_q && > + scsi_cmd_to_driver(next) == uld) > + next = list_next_entry(next, eh_entry); > + if (!uld->eh_prepare_resubmit) > + continue; > + prev = scmd->eh_entry.prev; > + list_cut_position(&uld_cmd_list, prev, next->eh_entry.prev); > + uld->eh_prepare_resubmit(&uld_cmd_list); > + list_splice(&uld_cmd_list, prev); > + } > +} > + > /** > * scsi_eh_flush_done_q - finish processed commands or retry them. > * @done_q: list_head of processed commands. > @@ -2194,6 +2264,8 @@ void scsi_eh_flush_done_q(struct list_head *done_q) > { > struct scsi_cmnd *scmd, *next; > > + scsi_call_prepare_resubmit(done_q); > + > list_for_each_entry_safe(scmd, next, done_q, eh_entry) { > list_del_init(&scmd->eh_entry); > if (scsi_device_online(scmd->device) && > diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h > index 3f0dfb97db6b..64070e530c4d 100644 > --- a/drivers/scsi/scsi_priv.h > +++ b/drivers/scsi/scsi_priv.h > @@ -101,6 +101,7 @@ int scsi_eh_get_sense(struct list_head *work_q, > struct list_head *done_q); > bool scsi_noretry_cmd(struct scsi_cmnd *scmd); > void scsi_eh_done(struct scsi_cmnd *scmd); > +void scsi_call_prepare_resubmit(struct list_head *done_q); > > /* scsi_lib.c */ > extern void scsi_device_unbusy(struct scsi_device *sdev, struct scsi_cmnd *cmd); > diff --git a/include/scsi/scsi_driver.h b/include/scsi/scsi_driver.h > index 4ce1988b2ba0..00ffa470724a 100644 > --- a/include/scsi/scsi_driver.h > +++ b/include/scsi/scsi_driver.h > @@ -18,6 +18,8 @@ struct scsi_driver { > int (*done)(struct scsi_cmnd *); > int (*eh_action)(struct scsi_cmnd *, int); > void (*eh_reset)(struct scsi_cmnd *); > + bool (*eh_needs_prepare_resubmit)(struct scsi_cmnd *cmd); > + void (*eh_prepare_resubmit)(struct list_head *cmd_list); > }; > #define to_scsi_driver(drv) \ > container_of((drv), struct scsi_driver, gendrv) -- Damien Le Moal Western Digital Research