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io_uring: don't rely on weak ->files references

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Grab actual references to the files_struct. To avoid circular references
issues due to this, we add a per-task note that keeps track of what
io_uring contexts a task has used. When the tasks execs or exits its
assigned files, we cancel requests based on this tracking.

With that, we can grab proper references to the files table, and no
longer need to rely on stashing away ring_fd and ring_file to check
if the ring_fd may have been closed.

Cc: stable@vger.kernel.org # v5.5+
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe
2020-09-13 13:09:39 -06:00
parent e6c8aa9ac3
commit 0f2122045b
7 changed files with 344 additions and 37 deletions
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53
include/linux/io_uring.h Normal file
View File

@@ -0,0 +1,53 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _LINUX_IO_URING_H
#define _LINUX_IO_URING_H
#include <linux/sched.h>
#include <linux/xarray.h>
#include <linux/percpu-refcount.h>
struct io_uring_task {
/* submission side */
struct xarray xa;
struct wait_queue_head wait;
struct file *last;
atomic_long_t req_issue;
/* completion side */
bool in_idle ____cacheline_aligned_in_smp;
atomic_long_t req_complete;
};
#if defined(CONFIG_IO_URING)
void __io_uring_task_cancel(void);
void __io_uring_files_cancel(struct files_struct *files);
void __io_uring_free(struct task_struct *tsk);
static inline void io_uring_task_cancel(void)
{
if (current->io_uring && !xa_empty(&current->io_uring->xa))
__io_uring_task_cancel();
}
static inline void io_uring_files_cancel(struct files_struct *files)
{
if (current->io_uring && !xa_empty(&current->io_uring->xa))
__io_uring_files_cancel(files);
}
static inline void io_uring_free(struct task_struct *tsk)
{
if (tsk->io_uring)
__io_uring_free(tsk);
}
#else
static inline void io_uring_task_cancel(void)
{
}
static inline void io_uring_files_cancel(struct files_struct *files)
{
}
static inline void io_uring_free(struct task_struct *tsk)
{
}
#endif
#endif