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Subject[PATCH 20/27] ip2: avoid add_timer with pending timer
Date
From: Akinobu Mita <akinobu.mita@gmail.com>

add_timer() is not suppose to be called when the timer is pending.
ip2 driver attempts to avoid that condition by setting and resetting
a flag (TimerOn) in timer function. But there is some gap between
add_timer() and setting TimerOn.

This patch fix this problem by using mod_timer() and remove TimerOn
which has been unnecessary by this change.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Alan Cox <alan@redhat.com>
---

drivers/char/ip2/ip2main.c | 19 ++++---------------
1 files changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c
index 39269d1..66f52a2 100644
--- a/drivers/char/ip2/ip2main.c
+++ b/drivers/char/ip2/ip2main.c
@@ -249,7 +249,6 @@ static unsigned long bh_counter;
*/
#define POLL_TIMEOUT (jiffies + 1)
static DEFINE_TIMER(PollTimer, ip2_poll, 0, 0);
-static char TimerOn;

#ifdef IP2DEBUG_TRACE
/* Trace (debug) buffer data */
@@ -374,11 +373,7 @@ static void __exit ip2_cleanup_module(void)
int err;
int i;

- /* Stop poll timer if we had one. */
- if (TimerOn) {
- del_timer(&PollTimer);
- TimerOn = 0;
- }
+ del_timer_sync(&PollTimer);

/* Reset the boards we have. */
for (i = 0; i < IP2_MAX_BOARDS; i++)
@@ -774,10 +769,8 @@ static int __init ip2_loadmain(void)
}
if (ip2config.irq[i] == CIR_POLL) {
retry:
- if (!TimerOn) {
- PollTimer.expires = POLL_TIMEOUT;
- add_timer(&PollTimer);
- TimerOn = 1;
+ if (!timer_pending(&PollTimer)) {
+ mod_timer(&PollTimer, POLL_TIMEOUT);
printk(KERN_INFO "IP2: polling\n");
}
} else {
@@ -1283,16 +1276,12 @@ ip2_poll(unsigned long arg)
{
ip2trace (ITRC_NO_PORT, ITRC_INTR, 100, 0 );

- TimerOn = 0; // it's the truth but not checked in service
-
// Just polled boards, IRQ = 0 will hit all non-interrupt boards.
// It will NOT poll boards handled by hard interrupts.
// The issue of queued BH interrupts is handled in ip2_interrupt().
ip2_polled_interrupt();

- PollTimer.expires = POLL_TIMEOUT;
- add_timer( &PollTimer );
- TimerOn = 1;
+ mod_timer(&PollTimer, POLL_TIMEOUT);

ip2trace (ITRC_NO_PORT, ITRC_INTR, ITRC_RETURN, 0 );
}


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