Revision cccd32816506cbac3a4c65d9dff51b3125ef1a03 authored by Lukas Wunner on 15 September 2023, 07:55:39 UTC, committed by Ingo Molnar on 15 September 2023, 09:28:08 UTC
Commit: 5a5d7e9badd2 ("cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG") amended warn_slowpath_fmt() to disable preemption until the WARN splat has been emitted. However the commit neglected to reenable preemption in the !fmt codepath, i.e. when a WARN splat is emitted without additional format string. One consequence is that users may see more splats than intended. E.g. a WARN splat emitted in a work item results in at least two extra splats: BUG: workqueue leaked lock or atomic (emitted by process_one_work()) BUG: scheduling while atomic (emitted by worker_thread() -> schedule()) Ironically the point of the commit was to *avoid* extra splats. ;) Fix it. Fixes: 5a5d7e9badd2 ("cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG") Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/r/3ec48fde01e4ee6505f77908ba351bad200ae3d1.1694763684.git.lukas@wunner.de
1 parent 9fdfb15
epoll.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io_uring.h>
#include <linux/eventpoll.h>
#include <uapi/linux/io_uring.h>
#include "io_uring.h"
#include "epoll.h"
#if defined(CONFIG_EPOLL)
struct io_epoll {
struct file *file;
int epfd;
int op;
int fd;
struct epoll_event event;
};
int io_epoll_ctl_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_epoll *epoll = io_kiocb_to_cmd(req, struct io_epoll);
if (sqe->buf_index || sqe->splice_fd_in)
return -EINVAL;
epoll->epfd = READ_ONCE(sqe->fd);
epoll->op = READ_ONCE(sqe->len);
epoll->fd = READ_ONCE(sqe->off);
if (ep_op_has_event(epoll->op)) {
struct epoll_event __user *ev;
ev = u64_to_user_ptr(READ_ONCE(sqe->addr));
if (copy_from_user(&epoll->event, ev, sizeof(*ev)))
return -EFAULT;
}
return 0;
}
int io_epoll_ctl(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_epoll *ie = io_kiocb_to_cmd(req, struct io_epoll);
int ret;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
ret = do_epoll_ctl(ie->epfd, ie->op, ie->fd, &ie->event, force_nonblock);
if (force_nonblock && ret == -EAGAIN)
return -EAGAIN;
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}
#endif
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