From patchwork Wed Sep 15 22:32:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Gilbert X-Patchwork-Id: 512682 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31378C433FE for ; Wed, 15 Sep 2021 22:41:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1FD3E60F70 for ; Wed, 15 Sep 2021 22:41:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232975AbhIOWmc (ORCPT ); Wed, 15 Sep 2021 18:42:32 -0400 Received: from smtp.infotech.no ([82.134.31.41]:36527 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232894AbhIOWma (ORCPT ); Wed, 15 Sep 2021 18:42:30 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id 444C02041CB; Thu, 16 Sep 2021 00:33:11 +0200 (CEST) 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 o1WM3szuvK6G; Thu, 16 Sep 2021 00:33:09 +0200 (CEST) Received: from xtwo70.bingwo.ca (host-45-78-207-107.dyn.295.ca [45.78.207.107]) by smtp.infotech.no (Postfix) with ESMTPA id 329152041AC; Thu, 16 Sep 2021 00:33:05 +0200 (CEST) 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, Hannes Reinecke Subject: [PATCH v20 06/46] sg: make open count an atomic Date: Wed, 15 Sep 2021 18:32:25 -0400 Message-Id: <20210915223305.256429-7-dgilbert@interlog.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210915223305.256429-1-dgilbert@interlog.com> References: <20210915223305.256429-1-dgilbert@interlog.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Convert sg_device::open_cnt into an atomic. Also rename sg_tablesize into the more descriptive max_sgat_elems. Reviewed-by: Hannes Reinecke Signed-off-by: Douglas Gilbert --- drivers/scsi/sg.c | 44 +++++++++++++++++++++++--------------------- 1 file changed, 23 insertions(+), 21 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 85552c4107ba..bf16b7c9639c 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -162,9 +162,9 @@ struct sg_device { /* holds the state of each scsi generic device */ struct mutex open_rel_lock; /* held when in open() or release() */ struct list_head sfds; rwlock_t sfd_lock; /* protect access to sfd list */ - int sg_tablesize; /* adapter's max scatter-gather table size */ + int max_sgat_elems; /* adapter's max sgat number of elements */ u32 index; /* device index number */ - int open_cnt; /* count of opens (perhaps < num(sfds) ) */ + atomic_t open_cnt; /* count of opens (perhaps < num(sfds) ) */ unsigned long fdev_bm[1]; /* see SG_FDEV_* defines above */ char name[DISK_NAME_LEN]; struct cdev *cdev; @@ -276,11 +276,11 @@ sg_wait_open_event(struct sg_device *sdp, bool o_excl) int retval = 0; if (o_excl) { - while (sdp->open_cnt > 0) { + while (atomic_read(&sdp->open_cnt) > 0) { mutex_unlock(&sdp->open_rel_lock); retval = wait_event_interruptible(sdp->open_wait, (SG_IS_DETACHING(sdp) || - !sdp->open_cnt)); + atomic_read(&sdp->open_cnt) == 0)); mutex_lock(&sdp->open_rel_lock); if (retval) /* -ERESTARTSYS */ @@ -328,7 +328,7 @@ sg_open(struct inode *inode, struct file *filp) o_excl = !!(op_flags & O_EXCL); if (o_excl && ((op_flags & O_ACCMODE) == O_RDONLY)) return -EPERM; /* Can't lock it with read only access */ - sdp = sg_get_dev(min_dev); + sdp = sg_get_dev(min_dev); /* increments sdp->d_ref */ if (IS_ERR(sdp)) return PTR_ERR(sdp); @@ -355,7 +355,7 @@ sg_open(struct inode *inode, struct file *filp) mutex_lock(&sdp->open_rel_lock); if (op_flags & O_NONBLOCK) { if (o_excl) { - if (sdp->open_cnt > 0) { + if (atomic_read(&sdp->open_cnt) > 0) { retval = -EBUSY; goto error_mutex_locked; } @@ -375,27 +375,29 @@ sg_open(struct inode *inode, struct file *filp) if (o_excl) set_bit(SG_FDEV_EXCLUDE, sdp->fdev_bm); - if (sdp->open_cnt < 1) { /* no existing opens */ + if (atomic_read(&sdp->open_cnt) < 1) { /* no existing opens */ clear_bit(SG_FDEV_LOG_SENSE, sdp->fdev_bm); q = sdp->device->request_queue; - sdp->sg_tablesize = queue_max_segments(q); + sdp->max_sgat_elems = queue_max_segments(q); } - sfp = sg_add_sfp(sdp); + sfp = sg_add_sfp(sdp); /* increments sdp->d_ref */ if (IS_ERR(sfp)) { retval = PTR_ERR(sfp); goto out_undo; } filp->private_data = sfp; - sdp->open_cnt++; + atomic_inc(&sdp->open_cnt); mutex_unlock(&sdp->open_rel_lock); SG_LOG(3, sfp, "%s: minor=%d, op_flags=0x%x; %s count prior=%d%s\n", - __func__, min_dev, op_flags, "device open", sdp->open_cnt, + __func__, min_dev, op_flags, "device open", + atomic_read(&sdp->open_cnt), ((op_flags & O_NONBLOCK) ? " O_NONBLOCK" : "")); retval = 0; sg_put: kref_put(&sdp->d_ref, sg_device_destroy); + /* if success, sdp->d_ref is incremented twice, decremented once */ return retval; out_undo: @@ -423,20 +425,20 @@ sg_release(struct inode *inode, struct file *filp) sfp = filp->private_data; sdp = sfp->parentdp; SG_LOG(3, sfp, "%s: device open count prior=%d\n", __func__, - sdp->open_cnt); + atomic_read(&sdp->open_cnt)); if (!sdp) return -ENXIO; mutex_lock(&sdp->open_rel_lock); scsi_autopm_put_device(sdp->device); kref_put(&sfp->f_ref, sg_remove_sfp); - sdp->open_cnt--; + atomic_dec(&sdp->open_cnt); /* possibly many open()s waiting on exclude clearing, start many; * only open(O_EXCL)s wait on 0==open_cnt so only start one */ if (test_and_clear_bit(SG_FDEV_EXCLUDE, sdp->fdev_bm)) wake_up_interruptible_all(&sdp->open_wait); - else if (sdp->open_cnt == 0) + else if (atomic_read(&sdp->open_cnt) == 0) wake_up_interruptible(&sdp->open_wait); mutex_unlock(&sdp->open_rel_lock); return 0; @@ -1112,7 +1114,7 @@ sg_ioctl_common(struct file *filp, struct sg_device *sdp, struct sg_fd *sfp, read_unlock_irqrestore(&sfp->rq_list_lock, iflags); return put_user(val, ip); case SG_GET_SG_TABLESIZE: - return put_user(sdp->sg_tablesize, ip); + return put_user(sdp->max_sgat_elems, ip); case SG_SET_RESERVED_SIZE: result = get_user(val, ip); if (result) @@ -1563,7 +1565,7 @@ sg_alloc(struct scsi_device *scsidp) init_waitqueue_head(&sdp->open_wait); clear_bit(SG_FDEV_DETACHING, sdp->fdev_bm); rwlock_init(&sdp->sfd_lock); - sdp->sg_tablesize = queue_max_segments(q); + sdp->max_sgat_elems = queue_max_segments(q); sdp->index = k; kref_init(&sdp->d_ref); error = 0; @@ -1948,7 +1950,7 @@ sg_build_indirect(struct sg_scatter_hold *schp, struct sg_fd *sfp, int buff_size) { int ret_sz = 0, i, k, rem_sz, num, mx_sc_elems; - int sg_tablesize = sfp->parentdp->sg_tablesize; + int max_sgat_elems = sfp->parentdp->max_sgat_elems; int blk_size = buff_size, order; gfp_t gfp_mask = GFP_ATOMIC | __GFP_COMP | __GFP_NOWARN | __GFP_ZERO; @@ -1962,7 +1964,7 @@ sg_build_indirect(struct sg_scatter_hold *schp, struct sg_fd *sfp, blk_size); /* N.B. ret_sz carried into this block ... */ - mx_sc_elems = sg_build_sgat(schp, sfp, sg_tablesize); + mx_sc_elems = sg_build_sgat(schp, sfp, max_sgat_elems); if (mx_sc_elems < 0) return mx_sc_elems; /* most likely -ENOMEM */ @@ -2646,9 +2648,9 @@ sg_proc_seq_show_debug(struct seq_file *s, void *v) scsidp->lun, scsidp->host->hostt->emulated); } - seq_printf(s, " sg_tablesize=%d excl=%d open_cnt=%d\n", - sdp->sg_tablesize, SG_HAVE_EXCLUDE(sdp), - sdp->open_cnt); + seq_printf(s, " max_sgat_elems=%d excl=%d open_cnt=%d\n", + sdp->max_sgat_elems, SG_HAVE_EXCLUDE(sdp), + atomic_read(&sdp->open_cnt)); sg_proc_debug_helper(s, sdp); } read_unlock(&sdp->sfd_lock);