Date: Wed, 29 Aug 2012 08:25:44 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-stable@freebsd.org Cc: Anton Yuzhaninov <citrin@citrin.ru> Subject: Re: Problem with IPMI KCS driver Message-ID: <201208290825.44198.jhb@freebsd.org> In-Reply-To: <503DE2AB.6030702@citrin.ru> References: <503DE2AB.6030702@citrin.ru>
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On Wednesday, August 29, 2012 5:36:43 am Anton Yuzhaninov wrote:
> We use servers witch motherboard Supermicro X8DTT-H and meet with such problem:
> when watchdogd started, server is rebooted by IPMI watchdog several times per week.
>
> After some debugging I've found, that sometimes IPMI driver entered endless
> loop, and watchdogd have no chances to reset watchdog timer.
> In such situation top show:
>
> PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND
> ...
> 113 root -16 - 0K 16K CPU4 4 17:18 99.17% ipmi0: kcs
>
> Endless loop located in file /sys/dev/ipmi/ipmi_kcs.c and function
> kcs_wait_for_obf():
>
> int status, start = ticks;
>
> status = INB(sc, KCS_CTL_STS);
> if (state == 0) {
> /* WAIT FOR OBF = 0 */
> while (ticks - start < MAX_TIMEOUT && status & KCS_STATUS_OBF) {
> DELAY(100);
> status = INB(sc, KCS_CTL_STS);
> }
> } else {
> /* WAIT FOR OBF = 1 */
> while (ticks - start < MAX_TIMEOUT &&
> !(status & KCS_STATUS_OBF)) {
> DELAY(100);
> status = INB(sc, KCS_CTL_STS);
> }
> }
>
> It seems to be, that this loop intended to run no more than MAX_TIMEOUT ticks.
> but by some reason this timeout does not works and loop runs until reboot.
>
> Questions:
> 1. Is it correct to check ticks to implement timeout here?
> 2. how to fix this timeout?
Hmm. Can you try this:
Index: kern/kern_clock.c
===================================================================
--- kern/kern_clock.c (revision 239819)
+++ kern/kern_clock.c (working copy)
@@ -382,7 +382,7 @@
int stathz;
int profhz;
int profprocs;
-int ticks;
+volatile int ticks;
int psratio;
static DPCPU_DEFINE(int, pcputicks); /* Per-CPU version of ticks. */
@@ -469,7 +469,7 @@
hardclock(int usermode, uintfptr_t pc)
{
- atomic_add_int((volatile int *)&ticks, 1);
+ atomic_add_int(&ticks, 1);
hardclock_cpu(usermode);
tc_ticktock(1);
cpu_tick_calibration();
Index: sys/kernel.h
===================================================================
--- sys/kernel.h (revision 239819)
+++ sys/kernel.h (working copy)
@@ -63,7 +63,7 @@
extern int stathz; /* statistics clock's frequency */
extern int profhz; /* profiling clock's frequency */
extern int profprocs; /* number of process's profiling */
-extern int ticks;
+extern volatile int ticks;
#endif /* _KERNEL */
--
John Baldwin
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