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Subject[PATCH 3/4] serdev: make synchronous write helper interruptible
Date
Allow the synchronous serdev_device_write() helper to be interrupted.

This is useful for cases where I/O is performed on behalf of user space
and we don't want to block indefinitely when using flow control.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/tty/serdev/core.c | 20 ++++++++++++++------
include/linux/serdev.h | 2 +-
2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index ee4c40336633..c7006bbb793a 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -231,7 +231,7 @@ EXPORT_SYMBOL_GPL(serdev_device_write_buf);

int serdev_device_write(struct serdev_device *serdev,
const unsigned char *buf, size_t count,
- unsigned long timeout)
+ long timeout)
{
struct serdev_controller *ctrl = serdev->ctrl;
int written = 0;
@@ -254,16 +254,24 @@ int serdev_device_write(struct serdev_device *serdev,
written += ret;
buf += ret;
count -= ret;
- } while (count &&
- (timeout = wait_for_completion_timeout(&serdev->write_comp,
- timeout)));
+
+ if (count == 0)
+ break;
+
+ timeout = wait_for_completion_interruptible_timeout(&serdev->write_comp,
+ timeout);
+ } while (timeout > 0);
mutex_unlock(&serdev->write_lock);

if (ret < 0)
return ret;

- if (timeout == 0 && written == 0)
- return -ETIMEDOUT;
+ if (timeout <= 0 && written == 0) {
+ if (timeout == -ERESTARTSYS)
+ return -ERESTARTSYS;
+ else
+ return -ETIMEDOUT;
+ }

return written;
}
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index f153b2c7f0cd..070bf4e92df7 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -210,7 +210,7 @@ void serdev_device_wait_until_sent(struct serdev_device *, long);
int serdev_device_get_tiocm(struct serdev_device *);
int serdev_device_set_tiocm(struct serdev_device *, int, int);
void serdev_device_write_wakeup(struct serdev_device *);
-int serdev_device_write(struct serdev_device *, const unsigned char *, size_t, unsigned long);
+int serdev_device_write(struct serdev_device *, const unsigned char *, size_t, long);
void serdev_device_write_flush(struct serdev_device *);
int serdev_device_write_room(struct serdev_device *);

--
2.19.1
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