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xen: privcmd: Switch from mutex to spinlock for irqfds
[ Upstream commit 1c68259309
]
irqfd_wakeup() gets EPOLLHUP, when it is called by
eventfd_release() by way of wake_up_poll(&ctx->wqh, EPOLLHUP), which
gets called under spin_lock_irqsave(). We can't use a mutex here as it
will lead to a deadlock.
Fix it by switching over to a spin lock.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/a66d7a7a9001424d432f52a9fc3931a1f345464f.1718703669.git.viresh.kumar@linaro.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
9747b72212
commit
c2775ae4d9
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@ -841,7 +841,7 @@ out:
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#ifdef CONFIG_XEN_PRIVCMD_IRQFD
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#ifdef CONFIG_XEN_PRIVCMD_IRQFD
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/* Irqfd support */
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/* Irqfd support */
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static struct workqueue_struct *irqfd_cleanup_wq;
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static struct workqueue_struct *irqfd_cleanup_wq;
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static DEFINE_MUTEX(irqfds_lock);
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static DEFINE_SPINLOCK(irqfds_lock);
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static LIST_HEAD(irqfds_list);
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static LIST_HEAD(irqfds_list);
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struct privcmd_kernel_irqfd {
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struct privcmd_kernel_irqfd {
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@ -905,9 +905,11 @@ irqfd_wakeup(wait_queue_entry_t *wait, unsigned int mode, int sync, void *key)
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irqfd_inject(kirqfd);
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irqfd_inject(kirqfd);
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if (flags & EPOLLHUP) {
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if (flags & EPOLLHUP) {
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mutex_lock(&irqfds_lock);
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unsigned long flags;
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spin_lock_irqsave(&irqfds_lock, flags);
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irqfd_deactivate(kirqfd);
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irqfd_deactivate(kirqfd);
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mutex_unlock(&irqfds_lock);
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spin_unlock_irqrestore(&irqfds_lock, flags);
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}
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}
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return 0;
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return 0;
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@ -925,6 +927,7 @@ irqfd_poll_func(struct file *file, wait_queue_head_t *wqh, poll_table *pt)
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static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
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static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
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{
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{
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struct privcmd_kernel_irqfd *kirqfd, *tmp;
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struct privcmd_kernel_irqfd *kirqfd, *tmp;
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unsigned long flags;
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__poll_t events;
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__poll_t events;
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struct fd f;
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struct fd f;
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void *dm_op;
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void *dm_op;
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@ -964,18 +967,18 @@ static int privcmd_irqfd_assign(struct privcmd_irqfd *irqfd)
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init_waitqueue_func_entry(&kirqfd->wait, irqfd_wakeup);
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init_waitqueue_func_entry(&kirqfd->wait, irqfd_wakeup);
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init_poll_funcptr(&kirqfd->pt, irqfd_poll_func);
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init_poll_funcptr(&kirqfd->pt, irqfd_poll_func);
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mutex_lock(&irqfds_lock);
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spin_lock_irqsave(&irqfds_lock, flags);
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list_for_each_entry(tmp, &irqfds_list, list) {
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list_for_each_entry(tmp, &irqfds_list, list) {
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if (kirqfd->eventfd == tmp->eventfd) {
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if (kirqfd->eventfd == tmp->eventfd) {
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ret = -EBUSY;
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ret = -EBUSY;
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mutex_unlock(&irqfds_lock);
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spin_unlock_irqrestore(&irqfds_lock, flags);
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goto error_eventfd;
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goto error_eventfd;
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}
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}
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}
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}
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list_add_tail(&kirqfd->list, &irqfds_list);
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list_add_tail(&kirqfd->list, &irqfds_list);
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mutex_unlock(&irqfds_lock);
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spin_unlock_irqrestore(&irqfds_lock, flags);
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/*
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/*
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* Check if there was an event already pending on the eventfd before we
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* Check if there was an event already pending on the eventfd before we
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@ -1007,12 +1010,13 @@ static int privcmd_irqfd_deassign(struct privcmd_irqfd *irqfd)
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{
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{
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struct privcmd_kernel_irqfd *kirqfd;
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struct privcmd_kernel_irqfd *kirqfd;
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struct eventfd_ctx *eventfd;
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struct eventfd_ctx *eventfd;
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unsigned long flags;
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eventfd = eventfd_ctx_fdget(irqfd->fd);
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eventfd = eventfd_ctx_fdget(irqfd->fd);
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if (IS_ERR(eventfd))
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if (IS_ERR(eventfd))
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return PTR_ERR(eventfd);
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return PTR_ERR(eventfd);
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mutex_lock(&irqfds_lock);
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spin_lock_irqsave(&irqfds_lock, flags);
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list_for_each_entry(kirqfd, &irqfds_list, list) {
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list_for_each_entry(kirqfd, &irqfds_list, list) {
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if (kirqfd->eventfd == eventfd) {
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if (kirqfd->eventfd == eventfd) {
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@ -1021,7 +1025,7 @@ static int privcmd_irqfd_deassign(struct privcmd_irqfd *irqfd)
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}
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}
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}
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}
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mutex_unlock(&irqfds_lock);
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spin_unlock_irqrestore(&irqfds_lock, flags);
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eventfd_ctx_put(eventfd);
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eventfd_ctx_put(eventfd);
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@ -1069,13 +1073,14 @@ static int privcmd_irqfd_init(void)
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static void privcmd_irqfd_exit(void)
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static void privcmd_irqfd_exit(void)
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{
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{
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struct privcmd_kernel_irqfd *kirqfd, *tmp;
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struct privcmd_kernel_irqfd *kirqfd, *tmp;
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unsigned long flags;
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mutex_lock(&irqfds_lock);
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spin_lock_irqsave(&irqfds_lock, flags);
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list_for_each_entry_safe(kirqfd, tmp, &irqfds_list, list)
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list_for_each_entry_safe(kirqfd, tmp, &irqfds_list, list)
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irqfd_deactivate(kirqfd);
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irqfd_deactivate(kirqfd);
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mutex_unlock(&irqfds_lock);
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spin_unlock_irqrestore(&irqfds_lock, flags);
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destroy_workqueue(irqfd_cleanup_wq);
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destroy_workqueue(irqfd_cleanup_wq);
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}
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}
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