Re: [BUG] mysterious tty deadlock

Andrew Morton (akpm@zip.com.au)
Wed, 28 Aug 2002 15:25:20 -0700


William Lee Irwin III wrote:
>
> One such stuck process had the following backtrace:
>
> #0 schedule_timeout (timeout=-150765944) at timer.c:864

schedule_timeout is FASTCALL, which confuses gdb's stack crawler
somewhat.

> #1 0xc01a28a3 in uart_wait_until_sent (tty=0xf7669000, timeout=2147483647)
> at core.c:1320

Might be a bit racy?

--- 2.5.32/drivers/serial/core.c~serial-race Wed Aug 28 15:22:22 2002
+++ 2.5.32-akpm/drivers/serial/core.c Wed Aug 28 15:22:26 2002
@@ -1315,13 +1315,14 @@ static void uart_wait_until_sent(struct
* 'timeout' / 'expire' give us the maximum amount of time
* we wait.
*/
+ set_current_state(TASK_INTERRUPTIBLE);
while (!port->ops->tx_empty(port)) {
- set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(char_time);
if (signal_pending(current))
break;
if (time_after(jiffies, expire))
break;
+ set_current_state(TASK_INTERRUPTIBLE);
}
set_current_state(TASK_RUNNING); /* might not be needed */
}

.
-
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