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authorRobin Holt <holt@sgi.com>2012-12-20 15:05:50 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-01-27 20:46:29 -0800
commit06cce029daed3ce1d98164b921bb3a826ad2a12a (patch)
treefc0e668206a0f909e3b1d16932cd1597ee8d3306
parentb6d3beb65f210873ef9a64a9fd204796e122da7c (diff)
downloadlwn-06cce029daed3ce1d98164b921bb3a826ad2a12a.tar.gz
lwn-06cce029daed3ce1d98164b921bb3a826ad2a12a.zip
SGI-XP: handle non-fatal traps
commit 891348ca0f66206f1dc0e30d63757e3df1ae2d15 upstream. We found a user code which was raising a divide-by-zero trap. That trap would lead to XPC connections between system-partitions being torn down due to the die_chain notifier callouts it received. This also revealed a different issue where multiple callers into xpc_die_deactivate() would all attempt to do the disconnect in parallel which would sometimes lock up but often overwhelm the console on very large machines as each would print at least one line of output at the end of the deactivate. I reviewed all the users of the die_chain notifier and changed the code to ignore the notifier callouts for reasons which will not actually lead to a system to continue on to call die(). [akpm@linux-foundation.org: fix ia64] Signed-off-by: Robin Holt <holt@sgi.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/misc/sgi-xp/xpc_main.c34
1 files changed, 32 insertions, 2 deletions
diff --git a/drivers/misc/sgi-xp/xpc_main.c b/drivers/misc/sgi-xp/xpc_main.c
index 8d082b46426b..d971817182f7 100644
--- a/drivers/misc/sgi-xp/xpc_main.c
+++ b/drivers/misc/sgi-xp/xpc_main.c
@@ -53,6 +53,10 @@
#include <linux/kthread.h>
#include "xpc.h"
+#ifdef CONFIG_X86_64
+#include <asm/traps.h>
+#endif
+
/* define two XPC debug device structures to be used with dev_dbg() et al */
struct device_driver xpc_dbg_name = {
@@ -1079,6 +1083,9 @@ xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
return NOTIFY_DONE;
}
+/* Used to only allow one cpu to complete disconnect */
+static unsigned int xpc_die_disconnecting;
+
/*
* Notify other partitions to deactivate from us by first disengaging from all
* references to our memory.
@@ -1092,6 +1099,9 @@ xpc_die_deactivate(void)
long keep_waiting;
long wait_to_print;
+ if (cmpxchg(&xpc_die_disconnecting, 0, 1))
+ return;
+
/* keep xpc_hb_checker thread from doing anything (just in case) */
xpc_exiting = 1;
@@ -1159,7 +1169,7 @@ xpc_die_deactivate(void)
* about the lack of a heartbeat.
*/
static int
-xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
+xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
{
#ifdef CONFIG_IA64 /* !!! temporary kludge */
switch (event) {
@@ -1191,7 +1201,27 @@ xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
break;
}
#else
- xpc_die_deactivate();
+ struct die_args *die_args = _die_args;
+
+ switch (event) {
+ case DIE_TRAP:
+ if (die_args->trapnr == X86_TRAP_DF)
+ xpc_die_deactivate();
+
+ if (((die_args->trapnr == X86_TRAP_MF) ||
+ (die_args->trapnr == X86_TRAP_XF)) &&
+ !user_mode_vm(die_args->regs))
+ xpc_die_deactivate();
+
+ break;
+ case DIE_INT3:
+ case DIE_DEBUG:
+ break;
+ case DIE_OOPS:
+ case DIE_GPF:
+ default:
+ xpc_die_deactivate();
+ }
#endif
return NOTIFY_DONE;