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author | attilio <attilio@FreeBSD.org> | 2009-08-13 17:09:45 +0000 |
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committer | attilio <attilio@FreeBSD.org> | 2009-08-13 17:09:45 +0000 |
commit | e85ca71aadcc42a3f7cc90e6cff96c28f1c54290 (patch) | |
tree | fa01b2cb8792e972d05922a5507e082efa4d4c1d /sys/kern/kern_shutdown.c | |
parent | b1786d80d2f6e85141431d158b4cf3a47a2f71ec (diff) | |
download | FreeBSD-src-e85ca71aadcc42a3f7cc90e6cff96c28f1c54290.zip FreeBSD-src-e85ca71aadcc42a3f7cc90e6cff96c28f1c54290.tar.gz |
* Completely Remove the option STOP_NMI from the kernel. This option
has proven to have a good effect when entering KDB by using a NMI,
but it completely violates all the good rules about interrupts
disabled while holding a spinlock in other occasions. This can be the
cause of deadlocks on events where a normal IPI_STOP is expected.
* Adds an new IPI called IPI_STOP_HARD on all the supported architectures.
This IPI is responsible for sending a stop message among CPUs using a
privileged channel when disponible. In other cases it just does match a
normal IPI_STOP.
Right now the IPI_STOP_HARD functionality uses a NMI on ia32 and amd64
architectures, while on the other has a normal IPI_STOP effect. It is
responsibility of maintainers to eventually implement an hard stop
when necessary and possible.
* Use the new IPI facility in order to implement a new userend SMP kernel
function called stop_cpus_hard(). That is specular to stop_cpu() but
it does use the privileged channel for the stopping facility.
* Let KDB use the newly introduced function stop_cpus_hard() and leave
stop_cpus() for all the other cases
* Disable interrupts on CPU0 when starting the process of APs suspension.
* Style cleanup and comments adding
This patch should fix the reboot/shutdown deadlocks many users are
constantly reporting on mailing lists.
Please don't forget to update your config file with the STOP_NMI
option removal
Reviewed by: jhb
Tested by: pho, bz, rink
Approved by: re (kib)
Diffstat (limited to 'sys/kern/kern_shutdown.c')
-rw-r--r-- | sys/kern/kern_shutdown.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c index 80dda97..0f3a672 100644 --- a/sys/kern/kern_shutdown.c +++ b/sys/kern/kern_shutdown.c @@ -412,9 +412,6 @@ boot(int howto) */ EVENTHANDLER_INVOKE(shutdown_post_sync, howto); - /* XXX This doesn't disable interrupts any more. Reconsider? */ - splhigh(); - if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) doadump(); @@ -488,6 +485,13 @@ static void shutdown_reset(void *junk, int howto) { + /* + * Disable interrupts on CPU0 in order to avoid fast handlers + * to preempt the stopping process and to deadlock against other + * CPUs. + */ + spinlock_enter(); + printf("Rebooting...\n"); DELAY(1000000); /* wait 1 sec for printf's to complete and be read */ /* cpu_boot(howto); */ /* doesn't do anything at the moment */ |