linux-kernel - [PATCH 3/4] um: chan: Restore blocking mode upon exit

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Date:   Sat,  1 Jan 2022 22:58:09 +0100
From:   Richard Weinberger <richard@....at>
To:     linux-um@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, johannes.berg@...el.com,
        anton.ivanov@...bridgegreys.com,
        Richard Weinberger <richard@....at>
Subject: [PATCH 3/4] um: chan: Restore blocking mode upon exit

Make sure that O_NONBLOCK is cleared upon exit if UML sets it.
Otherwise stdin/out behaves strange after UML terminates.

Signed-off-by: Richard Weinberger <richard@....at>
---
 arch/um/drivers/chan.h      | 1 +
 arch/um/drivers/chan_kern.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/arch/um/drivers/chan.h b/arch/um/drivers/chan.h
index c37cc4f26f91..6b8c462f146e 100644
--- a/arch/um/drivers/chan.h
+++ b/arch/um/drivers/chan.h
@@ -22,6 +22,7 @@ struct chan {
 	unsigned int output:1;
 	unsigned int opened:1;
 	unsigned int enabled:1;
+	unsigned int fd_blocking:1;
 	int fd;
 	const struct chan_ops *ops;
 	void *data;
diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index 86be115b5890..6d512589fa50 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -102,6 +102,7 @@ static int open_one_chan(struct chan *chan)
 	}
 
 	chan->fd = fd;
+	chan->fd_blocking = ret;
 
 	chan->opened = 1;
 	return 0;
@@ -223,6 +224,8 @@ static void close_one_chan(struct chan *chan, int delay_free_irq)
 	if (chan->ops->close != NULL)
 		(*chan->ops->close)(chan->fd, chan->data);
 
+	os_set_fd_block(chan->fd, chan->fd_blocking);
+
 	chan->opened = 0;
 	chan->fd = -1;
 }
-- 
2.26.2