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io_uring: disable polling pollfree files

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Older kernels lack io_uring POLLFREE handling. As only affected files
are signalfd and android binder the safest option would be to disable
polling those files via io_uring and hope there are no users.

Fixes: 221c5eb233 ("io_uring: add support for IORING_OP_POLL")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pavel Begunkov
2022-09-01 16:16:10 +01:00
committed by Greg Kroah-Hartman
parent 744b0d3080
commit 28d8d2737e
4 changed files with 8 additions and 0 deletions
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1
drivers/android/binder.c
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@@ -6069,6 +6069,7 @@ const struct file_operations binder_fops = {
.open = binder_open, .open = binder_open,
.flush = binder_flush, .flush = binder_flush,
.release = binder_release, .release = binder_release,
.may_pollfree = true,
}; };
static int __init init_binder_device(const char *name) static int __init init_binder_device(const char *name)

5
fs/io_uring.c
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@@ -5198,6 +5198,11 @@ static __poll_t __io_arm_poll_handler(struct io_kiocb *req,
struct io_ring_ctx *ctx = req->ctx; struct io_ring_ctx *ctx = req->ctx;
bool cancel = false; bool cancel = false;
if (req->file->f_op->may_pollfree) {
spin_lock_irq(&ctx->completion_lock);
return -EOPNOTSUPP;
}
INIT_HLIST_NODE(&req->hash_node); INIT_HLIST_NODE(&req->hash_node);
io_init_poll_iocb(poll, mask, wake_func); io_init_poll_iocb(poll, mask, wake_func);
poll->file = req->file; poll->file = req->file;

1
fs/signalfd.c
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@@ -248,6 +248,7 @@ static const struct file_operations signalfd_fops = {
.poll = signalfd_poll, .poll = signalfd_poll,
.read = signalfd_read, .read = signalfd_read,
.llseek = noop_llseek, .llseek = noop_llseek,
.may_pollfree = true,
}; };
static int do_signalfd4(int ufd, sigset_t *mask, int flags) static int do_signalfd4(int ufd, sigset_t *mask, int flags)

1
include/linux/fs.h
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@@ -1859,6 +1859,7 @@ struct file_operations {
struct file *file_out, loff_t pos_out, struct file *file_out, loff_t pos_out,
loff_t len, unsigned int remap_flags); loff_t len, unsigned int remap_flags);
int (*fadvise)(struct file *, loff_t, loff_t, int); int (*fadvise)(struct file *, loff_t, loff_t, int);
bool may_pollfree;
} __randomize_layout; } __randomize_layout;
struct inode_operations { struct inode_operations {