From patchwork Thu Sep 3 08:01:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11752603 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 1DCC414E5 for ; Thu, 3 Sep 2020 08:01:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F2F1C208CA for ; Thu, 3 Sep 2020 08:01:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="butYc1QG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728034AbgICIBh (ORCPT ); Thu, 3 Sep 2020 04:01:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60918 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727114AbgICIBc (ORCPT ); Thu, 3 Sep 2020 04:01:32 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2FB8CC061245; Thu, 3 Sep 2020 01:01:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=Eoe6FWuikvGSPhxu6V9VDQnUJRI7ZTy2sI/S1Ym9k6E=; b=butYc1QG1l6ganlb6TketniUKr ozDKsKMWtGmTDcBgl2/gkzJfGLAGBtabC52VFM2UBA+JdcI7XtIiWZ24GGGZBxXnbw8DYKGDMAeis NXNhA7Oz4ZMhPwJktapqiaOeTsXb8W7Q9dbVB9bOAeU+RrZvl9cXCIVNKmVRTp+/D6nOnrhHiIscv 5k+pUkM+s+O4eNTF/Xyd3Dt+jCPegD6zjOqpSft0/XsUqDOkQJKTYr7Jh2oboxzGNaC4bIYXHlw9L Qa4O+A1QzkhVrHAsosNgqbcKP/Rjs2/V2trEY7E4ftN0bYTm5pC5nr2/vl37ZtkE0IsjPBx0kosfc 6IGAlJ2Q==; Received: from [2001:4bb8:184:af1:c70:4a89:bc61:2] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDkBN-0006Zw-7B; Thu, 03 Sep 2020 08:01:21 +0000 From: Christoph Hellwig To: Jens Axboe Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , Denis Efremov , "David S. Miller" , Song Liu , Al Viro , Finn Thain , Michael Schmitz , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-raid@vger.kernel.org, linux-scsi@vger.kernel.org, linux-m68k@lists.linux-m68k.org Subject: [PATCH 01/19] char_dev: replace cdev_map with an xarray Date: Thu, 3 Sep 2020 10:01:01 +0200 Message-Id: <20200903080119.441674-2-hch@lst.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200903080119.441674-1-hch@lst.de> References: <20200903080119.441674-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org None of the complicated overlapping regions bits of the kobj_map are required for the character device lookup, so just a trivial xarray instead. Signed-off-by: Christoph Hellwig Reviewed-by: Greg Kroah-Hartman Reviewed-by: Hannes Reinecke --- fs/char_dev.c | 94 +++++++++++++++++++++++++-------------------------- fs/dcache.c | 1 - fs/internal.h | 5 --- 3 files changed, 47 insertions(+), 53 deletions(-) diff --git a/fs/char_dev.c b/fs/char_dev.c index ba0ded7842a779..f9a983d2d1a975 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -17,7 +17,6 @@ #include #include -#include #include #include #include @@ -25,8 +24,7 @@ #include "internal.h" -static struct kobj_map *cdev_map; - +static DEFINE_XARRAY(cdev_map); static DEFINE_MUTEX(chrdevs_lock); #define CHRDEV_MAJOR_HASH_SIZE 255 @@ -367,6 +365,29 @@ void cdev_put(struct cdev *p) } } +static struct cdev *cdev_lookup(dev_t dev) +{ + struct cdev *cdev; + +retry: + mutex_lock(&chrdevs_lock); + cdev = xa_load(&cdev_map, dev); + if (!cdev) { + mutex_unlock(&chrdevs_lock); + + if (request_module("char-major-%d-%d", + MAJOR(dev), MINOR(dev)) > 0) + /* Make old-style 2.4 aliases work */ + request_module("char-major-%d", MAJOR(dev)); + goto retry; + } + + if (!cdev_get(cdev)) + cdev = NULL; + mutex_unlock(&chrdevs_lock); + return cdev; +} + /* * Called every time a character special file is opened */ @@ -380,13 +401,10 @@ static int chrdev_open(struct inode *inode, struct file *filp) spin_lock(&cdev_lock); p = inode->i_cdev; if (!p) { - struct kobject *kobj; - int idx; spin_unlock(&cdev_lock); - kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx); - if (!kobj) + new = cdev_lookup(inode->i_rdev); + if (!new) return -ENXIO; - new = container_of(kobj, struct cdev, kobj); spin_lock(&cdev_lock); /* Check i_cdev again in case somebody beat us to it while we dropped the lock. */ @@ -454,18 +472,6 @@ const struct file_operations def_chr_fops = { .llseek = noop_llseek, }; -static struct kobject *exact_match(dev_t dev, int *part, void *data) -{ - struct cdev *p = data; - return &p->kobj; -} - -static int exact_lock(dev_t dev, void *data) -{ - struct cdev *p = data; - return cdev_get(p) ? 0 : -1; -} - /** * cdev_add() - add a char device to the system * @p: the cdev structure for the device @@ -478,7 +484,7 @@ static int exact_lock(dev_t dev, void *data) */ int cdev_add(struct cdev *p, dev_t dev, unsigned count) { - int error; + int error, i; p->dev = dev; p->count = count; @@ -486,14 +492,22 @@ int cdev_add(struct cdev *p, dev_t dev, unsigned count) if (WARN_ON(dev == WHITEOUT_DEV)) return -EBUSY; - error = kobj_map(cdev_map, dev, count, NULL, - exact_match, exact_lock, p); - if (error) - return error; + mutex_lock(&chrdevs_lock); + for (i = 0; i < count; i++) { + error = xa_insert(&cdev_map, dev + i, p, GFP_KERNEL); + if (error) + goto out_unwind; + } + mutex_unlock(&chrdevs_lock); kobject_get(p->kobj.parent); - return 0; + +out_unwind: + while (--i >= 0) + xa_erase(&cdev_map, dev + i); + mutex_unlock(&chrdevs_lock); + return error; } /** @@ -575,11 +589,6 @@ void cdev_device_del(struct cdev *cdev, struct device *dev) cdev_del(cdev); } -static void cdev_unmap(dev_t dev, unsigned count) -{ - kobj_unmap(cdev_map, dev, count); -} - /** * cdev_del() - remove a cdev from the system * @p: the cdev structure to be removed @@ -593,11 +602,16 @@ static void cdev_unmap(dev_t dev, unsigned count) */ void cdev_del(struct cdev *p) { - cdev_unmap(p->dev, p->count); + int i; + + mutex_lock(&chrdevs_lock); + for (i = 0; i < p->count; i++) + xa_erase(&cdev_map, p->dev + i); + mutex_unlock(&chrdevs_lock); + kobject_put(&p->kobj); } - static void cdev_default_release(struct kobject *kobj) { struct cdev *p = container_of(kobj, struct cdev, kobj); @@ -656,20 +670,6 @@ void cdev_init(struct cdev *cdev, const struct file_operations *fops) cdev->ops = fops; } -static struct kobject *base_probe(dev_t dev, int *part, void *data) -{ - if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0) - /* Make old-style 2.4 aliases work */ - request_module("char-major-%d", MAJOR(dev)); - return NULL; -} - -void __init chrdev_init(void) -{ - cdev_map = kobj_map_init(base_probe, &chrdevs_lock); -} - - /* Let modules do char dev stuff */ EXPORT_SYMBOL(register_chrdev_region); EXPORT_SYMBOL(unregister_chrdev_region); diff --git a/fs/dcache.c b/fs/dcache.c index ea0485861d9377..55e534ad6f8f7f 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -3233,5 +3233,4 @@ void __init vfs_caches_init(void) files_maxfiles_init(); mnt_init(); bdev_cache_init(); - chrdev_init(); } diff --git a/fs/internal.h b/fs/internal.h index 10517ece45167f..110e952e75a8aa 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -54,11 +54,6 @@ static inline void bd_forget(struct inode *inode) extern int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, get_block_t *get_block, struct iomap *iomap); -/* - * char_dev.c - */ -extern void __init chrdev_init(void); - /* * fs_context.c */