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From: Christoph Hellwig <hch@lst.de>
To: viro@zeniv.linux.org.uk
Cc: Avi Kivity <avi@scylladb.com>,
	linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
	netdev@vger.kernel.org, linux-api@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH 32/32] random: convert to ->poll_mask
Date: Tue, 15 May 2018 21:48:33 +0200	[thread overview]
Message-ID: <20180515194833.6906-33-hch@lst.de> (raw)
In-Reply-To: <20180515194833.6906-1-hch@lst.de>

The big change is that random_read_wait and random_write_wait are merged
into a single waitqueue that uses keyed wakeups.  Because wait_event_*
doesn't know about that this will lead to occassional spurious wakeups
in _random_read and add_hwgenerator_randomness, but wait_event_* is
designed to handle these and were are not in a a hot path there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/char/random.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index cd888d4ee605..a8fb0020ba5c 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -402,8 +402,7 @@ static struct poolinfo {
 /*
  * Static global variables
  */
-static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
-static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
+static DECLARE_WAIT_QUEUE_HEAD(random_wait);
 static struct fasync_struct *fasync;
 
 static DEFINE_SPINLOCK(random_ready_list_lock);
@@ -722,8 +721,8 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 
 		/* should we wake readers? */
 		if (entropy_bits >= random_read_wakeup_bits &&
-		    wq_has_sleeper(&random_read_wait)) {
-			wake_up_interruptible(&random_read_wait);
+		    wq_has_sleeper(&random_wait)) {
+			wake_up_interruptible_poll(&random_wait, POLLIN);
 			kill_fasync(&fasync, SIGIO, POLL_IN);
 		}
 		/* If the input pool is getting full, send some
@@ -1397,7 +1396,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
 	trace_debit_entropy(r->name, 8 * ibytes);
 	if (ibytes &&
 	    (r->entropy_count >> ENTROPY_SHIFT) < random_write_wakeup_bits) {
-		wake_up_interruptible(&random_write_wait);
+		wake_up_interruptible_poll(&random_wait, POLLOUT);
 		kill_fasync(&fasync, SIGIO, POLL_OUT);
 	}
 
@@ -1839,7 +1838,7 @@ _random_read(int nonblock, char __user *buf, size_t nbytes)
 		if (nonblock)
 			return -EAGAIN;
 
-		wait_event_interruptible(random_read_wait,
+		wait_event_interruptible(random_wait,
 			ENTROPY_BITS(&input_pool) >=
 			random_read_wakeup_bits);
 		if (signal_pending(current))
@@ -1876,14 +1875,17 @@ urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 	return ret;
 }
 
+static struct wait_queue_head *
+random_get_poll_head(struct file *file, __poll_t events)
+{
+	return &random_wait;
+}
+
 static __poll_t
-random_poll(struct file *file, poll_table * wait)
+random_poll_mask(struct file *file, __poll_t events)
 {
-	__poll_t mask;
+	__poll_t mask = 0;
 
-	poll_wait(file, &random_read_wait, wait);
-	poll_wait(file, &random_write_wait, wait);
-	mask = 0;
 	if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)
 		mask |= EPOLLIN | EPOLLRDNORM;
 	if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
@@ -1990,7 +1992,8 @@ static int random_fasync(int fd, struct file *filp, int on)
 const struct file_operations random_fops = {
 	.read  = random_read,
 	.write = random_write,
-	.poll  = random_poll,
+	.get_poll_head  = random_get_poll_head,
+	.poll_mask  = random_poll_mask,
 	.unlocked_ioctl = random_ioctl,
 	.fasync = random_fasync,
 	.llseek = noop_llseek,
@@ -2323,7 +2326,7 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
 	 * We'll be woken up again once below random_write_wakeup_thresh,
 	 * or when the calling thread is about to terminate.
 	 */
-	wait_event_interruptible(random_write_wait, kthread_should_stop() ||
+	wait_event_interruptible(random_wait, kthread_should_stop() ||
 			ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
 	mix_pool_bytes(poolp, buffer, count);
 	credit_entropy_bits(poolp, entropy);
-- 
2.17.0

  parent reply	other threads:[~2018-05-15 19:50 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-15 19:48 aio poll and a new in-kernel poll API V11 Christoph Hellwig
2018-05-15 19:48 ` [PATCH 01/32] fs: unexport poll_schedule_timeout Christoph Hellwig
2018-05-15 19:48 ` [PATCH 02/32] fs: cleanup do_pollfd Christoph Hellwig
2018-05-15 19:48 ` [PATCH 03/32] fs: update documentation to mention __poll_t and match the code Christoph Hellwig
2018-05-15 19:48 ` [PATCH 04/32] fs: add new vfs_poll and file_can_poll helpers Christoph Hellwig
2018-05-15 19:48 ` [PATCH 05/32] fs: introduce new ->get_poll_head and ->poll_mask methods Christoph Hellwig
2018-05-15 19:48 ` [PATCH 06/32] aio: simplify KIOCB_KEY handling Christoph Hellwig
2018-05-15 19:48 ` [PATCH 07/32] aio: simplify cancellation Christoph Hellwig
2018-05-15 19:48 ` [PATCH 08/32] aio: replace kiocb_set_cancel_fn with a cancel_kiocb file operation Christoph Hellwig
2018-05-20  5:27   ` Al Viro
2018-05-15 19:48 ` [PATCH 09/32] aio: add delayed cancel support Christoph Hellwig
2018-05-15 19:48 ` [PATCH 10/32] aio: implement IOCB_CMD_POLL Christoph Hellwig
2018-05-20  5:32   ` Al Viro
2018-05-20  7:33     ` Al Viro
2018-05-20 17:32       ` Christoph Hellwig
2018-05-15 19:48 ` [PATCH 11/32] net: refactor socket_poll Christoph Hellwig
2018-05-15 19:48 ` [PATCH 12/32] net: add support for ->poll_mask in proto_ops Christoph Hellwig
2018-05-15 19:48 ` [PATCH 13/32] net: remove sock_no_poll Christoph Hellwig
2018-05-15 19:48 ` [PATCH 14/32] net/tcp: convert to ->poll_mask Christoph Hellwig
2018-05-15 19:48 ` [PATCH 15/32] net/unix: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 16/32] net: convert datagram_poll users tp ->poll_mask Christoph Hellwig
2018-05-15 19:48 ` [PATCH 17/32] net/dccp: convert to ->poll_mask Christoph Hellwig
2018-05-15 19:48 ` [PATCH 18/32] net/atm: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 19/32] net/vmw_vsock: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 20/32] net/tipc: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 21/32] net/sctp: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 22/32] net/bluetooth: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 23/32] net/caif: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 24/32] net/nfc: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 25/32] net/phonet: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 26/32] net/iucv: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 27/32] net/rxrpc: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 28/32] crypto: af_alg: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 29/32] pipe: " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 30/32] eventfd: switch " Christoph Hellwig
2018-05-15 19:48 ` [PATCH 31/32] timerfd: convert " Christoph Hellwig
2018-05-15 19:48 ` Christoph Hellwig [this message]
  -- strict thread matches above, loose matches on Subject: below --
2018-05-11 11:07 aio poll and a new in-kernel poll API V10 Christoph Hellwig
2018-05-11 11:08 ` [PATCH 32/32] random: convert to ->poll_mask Christoph Hellwig
2018-03-30 15:07 aio poll and a new in-kernel poll API V9 Christoph Hellwig
2018-03-30 15:08 ` [PATCH 32/32] random: convert to ->poll_mask Christoph Hellwig

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