From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Denis Efremov <efremov@linux.com>,
"David S. Miller" <davem@davemloft.net>,
Song Liu <song@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
Finn Thain <fthain@telegraphics.com.au>,
Michael Schmitz <schmitzmic@gmail.com>,
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 [thread overview]
Message-ID: <20200903080119.441674-2-hch@lst.de> (raw)
In-Reply-To: <20200903080119.441674-1-hch@lst.de>
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 <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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 <linux/seq_file.h>
#include <linux/kobject.h>
-#include <linux/kobj_map.h>
#include <linux/cdev.h>
#include <linux/mutex.h>
#include <linux/backing-dev.h>
@@ -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
*/
--
2.28.0
next prev parent reply other threads:[~2020-09-03 8:01 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 8:01 simplify gendisk lookup and remove struct block_device aliases v3 Christoph Hellwig
2020-09-03 8:01 ` Christoph Hellwig [this message]
2020-09-04 10:16 ` [PATCH 01/19] char_dev: replace cdev_map with an xarray Hannes Reinecke
2020-09-03 8:01 ` [PATCH 02/19] block: merge drivers/base/map.c into block/genhd.c Christoph Hellwig
2020-09-04 10:17 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 03/19] block: cleanup del_gendisk a bit Christoph Hellwig
2020-09-04 10:18 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 04/19] block: split block_class_lock Christoph Hellwig
2020-09-04 10:19 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 05/19] block: rework requesting modules for unclaimed devices Christoph Hellwig
2020-09-04 10:20 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 06/19] block: add an optional probe callback to major_names Christoph Hellwig
2020-09-04 10:20 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 07/19] ide: remove ide_{,un}register_region Christoph Hellwig
2020-09-03 8:01 ` [PATCH 08/19] swim: don't call blk_register_region Christoph Hellwig
2020-09-04 10:21 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 09/19] sd: use __register_blkdev to avoid a modprobe for an unregistered dev_t Christoph Hellwig
2020-09-04 10:22 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 10/19] brd: use __register_blkdev to allocate devices on demand Christoph Hellwig
2020-09-04 10:23 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 11/19] loop: " Christoph Hellwig
2020-09-04 10:24 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 12/19] md: " Christoph Hellwig
2020-09-04 10:25 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 13/19] ide: switch to __register_blkdev for command set probing Christoph Hellwig
2020-09-04 10:26 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 14/19] floppy: use a separate gendisk for each media format Christoph Hellwig
2020-09-04 9:59 ` Denis Efremov
2020-09-04 10:28 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 15/19] amiflop: use separate gendisks for Amiga vs MS-DOS mode Christoph Hellwig
2020-09-04 10:28 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 16/19] ataflop: use a separate gendisk for each media format Christoph Hellwig
2020-09-03 8:14 ` John Paul Adrian Glaubitz
2020-09-04 10:29 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 17/19] z2ram: reindent Christoph Hellwig
2020-09-04 10:29 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 18/19] z2ram: use separate gendisk for the different modes Christoph Hellwig
2020-09-04 10:30 ` Hannes Reinecke
2020-09-03 8:01 ` [PATCH 19/19] block: switch gendisk lookup to a simple xarray Christoph Hellwig
2020-09-04 10:30 ` Hannes Reinecke
-- strict thread matches above, loose matches on Subject: below --
2020-08-30 6:24 simplify gendisk lookup and remove struct block_device aliases v2 Christoph Hellwig
2020-08-30 6:24 ` [PATCH 01/19] char_dev: replace cdev_map with an xarray Christoph Hellwig
2020-08-30 7:31 ` Greg Kroah-Hartman
2020-08-26 6:24 simplify gendisk lookup and remove struct block_device aliases Christoph Hellwig
2020-08-26 6:24 ` [PATCH 01/19] char_dev: replace cdev_map with an xarray Christoph Hellwig
2020-08-26 8:19 ` Greg Kroah-Hartman
2020-08-27 8:53 ` Christoph Hellwig
2020-08-27 9:18 ` Greg Kroah-Hartman
2020-08-27 9:39 ` Christoph Hellwig
2020-08-27 7:25 ` Hannes Reinecke
2020-08-27 8:55 ` Christoph Hellwig
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