From: George Anzinger Date: Sat, 3 Sep 2005 22:56:48 +0000 (-0700) Subject: [PATCH] x86 NMI: better support for debuggers X-Git-Tag: v2.6.14-rc1~845 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=748f2edb52712aa3d926470a888608dc500d17e8;p=linux-2.6 [PATCH] x86 NMI: better support for debuggers This patch adds a notify to the die_nmi notify that the system is about to be taken down. If the notify is handled with a NOTIFY_STOP return, the system is given a new lease on life. We also change the nmi watchdog to carry on if die_nmi returns. This give debug code a chance to a) catch watchdog timeouts and b) possibly allow the system to continue, realizing that the time out may be due to debugger activities such as single stepping which is usually done with "other" cpus held. Signed-off-by: George Anzinger Cc: Keith Owens Signed-off-by: George Anzinger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c index 8c242bb1ef..8bbdbda07a 100644 --- a/arch/i386/kernel/nmi.c +++ b/arch/i386/kernel/nmi.c @@ -501,8 +501,11 @@ void nmi_watchdog_tick (struct pt_regs * regs) */ alert_counter[cpu]++; if (alert_counter[cpu] == 5*nmi_hz) + /* + * die_nmi will return ONLY if NOTIFY_STOP happens.. + */ die_nmi(regs, "NMI Watchdog detected LOCKUP"); - } else { + last_irq_sums[cpu] = sum; alert_counter[cpu] = 0; } diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c index b2b4bb890b..54629bb589 100644 --- a/arch/i386/kernel/traps.c +++ b/arch/i386/kernel/traps.c @@ -565,6 +565,10 @@ static DEFINE_SPINLOCK(nmi_print_lock); void die_nmi (struct pt_regs *regs, const char *msg) { + if (notify_die(DIE_NMIWATCHDOG, msg, regs, 0, 0, SIGINT) == + NOTIFY_STOP) + return; + spin_lock(&nmi_print_lock); /* * We are in trouble anyway, lets at least try diff --git a/include/asm-i386/kdebug.h b/include/asm-i386/kdebug.h index b3f8d5f59d..316138e899 100644 --- a/include/asm-i386/kdebug.h +++ b/include/asm-i386/kdebug.h @@ -41,9 +41,16 @@ enum die_val { DIE_PAGE_FAULT, }; -static inline int notify_die(enum die_val val,char *str,struct pt_regs *regs,long err,int trap, int sig) +static inline int notify_die(enum die_val val, const char *str, + struct pt_regs *regs, long err, int trap, int sig) { - struct die_args args = { .regs=regs, .str=str, .err=err, .trapnr=trap,.signr=sig }; + struct die_args args = { + .regs = regs, + .str = str, + .err = err, + .trapnr = trap, + .signr = sig + }; return notifier_call_chain(&i386die_chain, val, &args); }