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| author |   Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2021-02-16 19:27:14 +0100 |
|---|---|---|
| committer |   Miguel Ojeda <ojeda@kernel.org> | 2021-03-16 16:32:40 +0100 |
| commit | 701454bce906241ba7f50e2773881560d6404d29 (patch) | |
| tree | c37ca8b84e8ca8f626dfea29d07831af9b18d571 /drivers/auxdisplay | |
| parent | Linux 5.12-rc3 (diff) | |
| download | linux-dev-701454bce906241ba7f50e2773881560d6404d29.tar.xz linux-dev-701454bce906241ba7f50e2773881560d6404d29.zip | |
auxdisplay: Remove in_interrupt() usage.
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. in_interrupt() and related
context checks are being removed from non-core code.
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
iterations if needed.
Link: https://lkml.kernel.org/r/20200914204209.256266093@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[mo: fixed a couple typos in comment and commit message]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'drivers/auxdisplay')
| -rw-r--r-- | drivers/auxdisplay/charlcd.c | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c index f43430e9dcee..24fd6f369ebe 100644 --- a/drivers/auxdisplay/charlcd.c +++ b/drivers/auxdisplay/charlcd.c @@ -470,12 +470,14 @@ 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)) + if (((count + 1) & 0x1f) == 0) { /* - * let's be a little nice with other processes - * that need some CPU + * charlcd_write() is invoked as a VFS->write() callback + * and as such it is always invoked from preemptible + * context and may sleep. */ - schedule(); + cond_resched(); + } if (get_user(c, tmp)) return -EFAULT; @@ -537,12 +539,8 @@ 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); } |