charlcd_write() is invoked as a VFS->write() callback and as such it is always invoked from preemptible context and may sleep.
charlcd_puts() is invoked from register/unregister callback which is preemptible. The reboot notifier callback is also invoked from preemptible context. Therefore there is no need to use `in_interrupt()' to figure out if it is safe to sleep because it always is. Using `schedule()' to schedule (and be friendly to others) is discouraged and `cond_resched()' should be used instead. Remove `in_interrupt()' and use `cond_resched()' to schedule every 32 iteration if needed. Cc: Miguel Ojeda Sandonis <miguel.ojeda.sando...@gmail.com> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de> --- v1…v2: Spelling fixes. drivers/auxdisplay/charlcd.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c index f43430e9dceed..fbfce95919f72 100644 --- a/drivers/auxdisplay/charlcd.c +++ b/drivers/auxdisplay/charlcd.c @@ -470,12 +470,8 @@ static ssize_t charlcd_write(struct file *file, const char __user *buf, char c; for (; count-- > 0; (*ppos)++, tmp++) { - if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) - /* - * let's be a little nice with other processes - * that need some CPU - */ - schedule(); + if (((count + 1) & 0x1f) == 0) + cond_resched(); if (get_user(c, tmp)) return -EFAULT; @@ -537,12 +533,8 @@ static void charlcd_puts(struct charlcd *lcd, const char *s) int count = strlen(s); for (; count-- > 0; tmp++) { - if (!in_interrupt() && (((count + 1) & 0x1f) == 0)) - /* - * let's be a little nice with other processes - * that need some CPU - */ - schedule(); + if (((count + 1) & 0x1f) == 0) + cond_resched(); charlcd_write_char(lcd, *tmp); } -- 2.30.0