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authorArnd Bergmann <arnd@arndb.de>2014-01-02 13:07:38 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-07 17:05:21 -0800
commit591cee0a35632031cd925392a1bce507dcfe9ea8 (patch)
treedeb6628428c2f3b88f98846f1928658dbf43cb34 /drivers/tty
parentf8e87cb4a19aa5f5a1ce22e130da0f4a7fa2d5f3 (diff)
downloadop-kernel-dev-591cee0a35632031cd925392a1bce507dcfe9ea8.zip
op-kernel-dev-591cee0a35632031cd925392a1bce507dcfe9ea8.tar.gz
tty/amiserial: avoid interruptible_sleep_on
interruptible_sleep_on is generally problematic and we want to get rid of it. In case of TIOCMIWAIT, that race is actually in user space and does not get fixed since we can only detect changes after entering the ioctl handler, but it removes one more caller. This instance can not be trivially replaced with wait_event, so I chose to open-code the wait loop using prepare_to_wait/finish_wait. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/amiserial.c26
1 files changed, 18 insertions, 8 deletions
diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 71630a2..979e7c3 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -1248,6 +1248,8 @@ static int rs_ioctl(struct tty_struct *tty,
struct async_icount cprev, cnow; /* kernel counter temps */
void __user *argp = (void __user *)arg;
unsigned long flags;
+ DEFINE_WAIT(wait);
+ int ret;
if (serial_paranoia_check(info, tty->name, "rs_ioctl"))
return -ENODEV;
@@ -1288,25 +1290,33 @@ static int rs_ioctl(struct tty_struct *tty,
cprev = info->icount;
local_irq_restore(flags);
while (1) {
- interruptible_sleep_on(&info->tport.delta_msr_wait);
- /* see if a signal did it */
- if (signal_pending(current))
- return -ERESTARTSYS;
+ prepare_to_wait(&info->tport.delta_msr_wait,
+ &wait, TASK_INTERRUPTIBLE);
local_irq_save(flags);
cnow = info->icount; /* atomic copy */
local_irq_restore(flags);
if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
- cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
- return -EIO; /* no change => error */
+ cnow.dcd == cprev.dcd && cnow.cts == cprev.cts) {
+ ret = -EIO; /* no change => error */
+ break;
+ }
if ( ((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
((arg & TIOCM_CD) && (cnow.dcd != cprev.dcd)) ||
((arg & TIOCM_CTS) && (cnow.cts != cprev.cts)) ) {
- return 0;
+ ret = 0;
+ break;
+ }
+ schedule();
+ /* see if a signal did it */
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
}
cprev = cnow;
}
- /* NOTREACHED */
+ finish_wait(&info->tport.delta_msr_wait, &wait);
+ return ret;
case TIOCSERGWILD:
case TIOCSERSWILD:
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