Revision 5e98e916f95bdc50e90f3199d7f3d74b94fa5976 authored by Linus Torvalds on 12 February 2023, 21:52:17 UTC, committed by Linus Torvalds on 12 February 2023, 21:52:17 UTC
Pull tracing fix from Steven Rostedt: "Fix showing of TASK_COMM_LEN instead of its value The TASK_COMM_LEN was converted from a macro into an enum so that BTF would have access to it. But this unfortunately caused TASK_COMM_LEN to display in the format fields of trace events, as they are created by the TRACE_EVENT() macro and such, macros convert to their values, where as enums do not. To handle this, instead of using the field itself to be display, save the value of the array size as another field in the trace_event_fields structure, and use that instead. Not only does this fix the issue, but also converts the other trace events that have this same problem (but were not breaking tooling). With this change, the original work around b3bc8547d3be6 ("tracing: Have TRACE_DEFINE_ENUM affect trace event types as well") could be reverted (but that should be done in the merge window)" * tag 'trace-v6.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing: Fix TASK_COMM_LEN in trace event format file
holder.c
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/blkdev.h>
#include <linux/slab.h>
struct bd_holder_disk {
struct list_head list;
struct kobject *holder_dir;
int refcnt;
};
static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
struct gendisk *disk)
{
struct bd_holder_disk *holder;
list_for_each_entry(holder, &disk->slave_bdevs, list)
if (holder->holder_dir == bdev->bd_holder_dir)
return holder;
return NULL;
}
static int add_symlink(struct kobject *from, struct kobject *to)
{
return sysfs_create_link(from, to, kobject_name(to));
}
static void del_symlink(struct kobject *from, struct kobject *to)
{
sysfs_remove_link(from, kobject_name(to));
}
/**
* bd_link_disk_holder - create symlinks between holding disk and slave bdev
* @bdev: the claimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* This functions creates the following sysfs symlinks.
*
* - from "slaves" directory of the holder @disk to the claimed @bdev
* - from "holders" directory of the @bdev to the holder @disk
*
* For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
* passed to bd_link_disk_holder(), then:
*
* /sys/block/dm-0/slaves/sda --> /sys/block/sda
* /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
*
* The caller must have claimed @bdev before calling this function and
* ensure that both @bdev and @disk are valid during the creation and
* lifetime of these symlinks.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
int ret = 0;
if (WARN_ON_ONCE(!disk->slave_dir))
return -EINVAL;
if (bdev->bd_disk == disk)
return -EINVAL;
/*
* del_gendisk drops the initial reference to bd_holder_dir, so we
* need to keep our own here to allow for cleanup past that point.
*/
mutex_lock(&bdev->bd_disk->open_mutex);
if (!disk_live(bdev->bd_disk)) {
mutex_unlock(&bdev->bd_disk->open_mutex);
return -ENODEV;
}
kobject_get(bdev->bd_holder_dir);
mutex_unlock(&bdev->bd_disk->open_mutex);
mutex_lock(&disk->open_mutex);
WARN_ON_ONCE(!bdev->bd_holder);
holder = bd_find_holder_disk(bdev, disk);
if (holder) {
kobject_put(bdev->bd_holder_dir);
holder->refcnt++;
goto out_unlock;
}
holder = kzalloc(sizeof(*holder), GFP_KERNEL);
if (!holder) {
ret = -ENOMEM;
goto out_unlock;
}
INIT_LIST_HEAD(&holder->list);
holder->refcnt = 1;
holder->holder_dir = bdev->bd_holder_dir;
ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
if (ret)
goto out_free_holder;
ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
if (ret)
goto out_del_symlink;
list_add(&holder->list, &disk->slave_bdevs);
mutex_unlock(&disk->open_mutex);
return 0;
out_del_symlink:
del_symlink(disk->slave_dir, bdev_kobj(bdev));
out_free_holder:
kfree(holder);
out_unlock:
mutex_unlock(&disk->open_mutex);
if (ret)
kobject_put(bdev->bd_holder_dir);
return ret;
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
/**
* bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
* @bdev: the calimed slave bdev
* @disk: the holding disk
*
* DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
*
* CONTEXT:
* Might sleep.
*/
void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
if (WARN_ON_ONCE(!disk->slave_dir))
return;
mutex_lock(&disk->open_mutex);
holder = bd_find_holder_disk(bdev, disk);
if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
del_symlink(disk->slave_dir, bdev_kobj(bdev));
del_symlink(holder->holder_dir, &disk_to_dev(disk)->kobj);
kobject_put(holder->holder_dir);
list_del_init(&holder->list);
kfree(holder);
}
mutex_unlock(&disk->open_mutex);
}
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
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