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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2021-02-16 19:27:14 +0100
committerMiguel Ojeda <ojeda@kernel.org>2021-03-16 16:32:40 +0100
commit701454bce906241ba7f50e2773881560d6404d29 (patch)
treec37ca8b84e8ca8f626dfea29d07831af9b18d571
parent1e28eed17697bcf343c6743f0028cc3b5dd88bf0 (diff)
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>
-rw-r--r--drivers/auxdisplay/charlcd.c18
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);
}