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gpio: mockup: fix debugfs read

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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: 2a9e27408e ("gpio: mockup: rework debugfs interface")
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
This commit is contained in:
Bartosz Golaszewski 2019-03-22 18:27:12 +01:00
parent fa59dd234c
commit 2583303deb
1 changed files with 6 additions and 4 deletions
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10
drivers/gpio/gpio-mockup.c
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@ -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,