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| author | Bartosz Golaszewski <bgolaszewski@baylibre.com> | 2019-03-22 18:27:12 +0100 |
|---|---|---|
| committer | Bartosz Golaszewski <bgolaszewski@baylibre.com> | 2019-03-27 09:56:01 +0100 |
| commit | 2583303debb7acc77295b77901916d08a4c743c2 (patch) | |
| tree | dcafb0c6f74db205d336c9b9c10e0ff37c687666 | |
| parent | fa59dd234c9a237e590a5f6db530d7f7ee88e5e8 (diff) | |
| download | linux-0-day-2583303debb7acc77295b77901916d08a4c743c2.tar.gz linux-0-day-2583303debb7acc77295b77901916d08a4c743c2.tar.xz | |
gpio: mockup: fix debugfs read
The debugfs read callback must advance ppos or users using read() on
the file descriptor will never get the EOL. This wasn't spotted before
as I was using busybox cat for testing which uses sendfile() internally
and only noticed it now when switched to cat from coreutils.
Fixes: 2a9e27408e12 ("gpio: mockup: rework debugfs interface")
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
| -rw-r--r-- | drivers/gpio/gpio-mockup.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c index 154d959e89932..74ba8b1d71d87 100644 --- a/drivers/gpio/gpio-mockup.c +++ b/drivers/gpio/gpio-mockup.c @@ -204,8 +204,9 @@ static ssize_t gpio_mockup_debugfs_read(struct file *file, struct gpio_mockup_chip *chip; struct seq_file *sfile; struct gpio_chip *gc; + int val, rv, cnt; char buf[3]; - int val, rv; + if (*ppos != 0) return 0; @@ -216,13 +217,14 @@ static ssize_t gpio_mockup_debugfs_read(struct file *file, gc = &chip->gc; val = gpio_mockup_get(gc, priv->offset); - snprintf(buf, sizeof(buf), "%d\n", val); + cnt = snprintf(buf, sizeof(buf), "%d\n", val); - rv = copy_to_user(usr_buf, buf, sizeof(buf)); + rv = copy_to_user(usr_buf, buf, cnt); if (rv) return rv; - return sizeof(buf) - 1; + *ppos += cnt; + return cnt; } static ssize_t gpio_mockup_debugfs_write(struct file *file, |