From patchwork Sat Jul 27 03:37:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Gilbert X-Patchwork-Id: 11062185 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 125CE56FC for ; Sat, 27 Jul 2019 03:38:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ECB8F28B8D for ; Sat, 27 Jul 2019 03:38:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5994928B9D; Sat, 27 Jul 2019 03:37:50 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D327328B9C for ; Sat, 27 Jul 2019 03:37:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727643AbfG0Dht (ORCPT ); Fri, 26 Jul 2019 23:37:49 -0400 Received: from smtp.infotech.no ([82.134.31.41]:54545 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727340AbfG0Dhs (ORCPT ); Fri, 26 Jul 2019 23:37:48 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id C335B20419A; Sat, 27 Jul 2019 05:37:47 +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 YAz+XKO5e5UC; Sat, 27 Jul 2019 05:37:46 +0200 (CEST) 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 9898820419B; Sat, 27 Jul 2019 05:37:44 +0200 (CEST) From: Douglas Gilbert To: linux-scsi@vger.kernel.org Cc: martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, hare@suse.de, bart.vanassche@wdc.com Subject: [PATCH v2 06/18] sg: make open count an atomic Date: Fri, 26 Jul 2019 23:37:16 -0400 Message-Id: <20190727033728.21134-7-dgilbert@interlog.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190727033728.21134-1-dgilbert@interlog.com> References: <20190727033728.21134-1-dgilbert@interlog.com> Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Convert sg_device::open_cnt into an atomic. Also rename sg_tablesize into the more descriptive max_sgat_elems. Signed-off-by: Douglas Gilbert Reviewed-by: Hannes Reinecke --- drivers/scsi/sg.c | 39 ++++++++++++++++++++------------------- 1 file changed, 20 insertions(+), 19 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 97ce84f0c51b..9e9470944fe3 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 */ struct gendisk *disk; struct cdev * cdev; /* char_dev [sysfs: /sys/cdev/major/sg] */ @@ -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 */ @@ -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; } @@ -375,10 +375,10 @@ 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); if (IS_ERR(sfp)) { @@ -387,10 +387,11 @@ sg_open(struct inode *inode, struct file *filp) } 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; @@ -423,20 +424,20 @@ 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 exlude 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; @@ -1104,7 +1105,7 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg) 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 +1564,7 @@ sg_alloc(struct gendisk *disk, 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; @@ -1958,7 +1959,7 @@ 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; struct sg_device *sdp = sfp->parentdp; @@ -1973,7 +1974,7 @@ 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 */ @@ -2662,9 +2663,9 @@ 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);