From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keith Owens Date: Tue, 16 Oct 2001 02:46:45 +0000 Subject: [Linux-ia64] [patch] ia64-011010 die() deadlock Message-Id: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Any die() routine that uses die_lock to avoid multiple cpu reentrancy will deadlock on recursive die() errors. This patch fixes ia64-011010. Andrew Morton, who did the original die_lock code, agrees that this is required. The code makes best effort at diagnosing the first recursive error then gives up. This patch removes the only reference to IA64_KERNEL_DEATH so I deleted the flag as well. Index: 11.7/arch/ia64/kernel/traps.c --- 11.7/arch/ia64/kernel/traps.c Thu, 11 Oct 2001 14:03:29 +1000 kaos (linux-2.4/r/c/43_traps.c 1.1.4.1.3.4 644) +++ 11.7(w)/arch/ia64/kernel/traps.c Tue, 16 Oct 2001 12:33:57 +1000 kaos (linux-2.4/r/c/43_traps.c 1.1.4.1.3.4 644) @@ -88,21 +89,26 @@ void die (const char *str, struct pt_regs *regs, long err) { static spinlock_t die_lock = SPIN_LOCK_UNLOCKED; + static int die_lock_owner = -1, die_lock_owner_depth = 0; - console_verbose(); - spin_lock_irq(&die_lock); - bust_spinlocks(1); - printk("%s[%d]: %s %ld\n", current->comm, current->pid, str, err); - show_regs(regs); - bust_spinlocks(0); - spin_unlock_irq(&die_lock); + if (die_lock_owner != smp_processor_id()) { + console_verbose(); + spin_lock_irq(&die_lock); + die_lock_owner = smp_processor_id(); + die_lock_owner_depth = 0; + bust_spinlocks(1); + } - if (current->thread.flags & IA64_KERNEL_DEATH) { - printk("die_if_kernel recursion detected.\n"); - sti(); - while (1); + if (++die_lock_owner_depth < 3) { + printk("%s[%d]: %s %ld\n", current->comm, current->pid, str, err); + show_regs(regs); } - current->thread.flags |= IA64_KERNEL_DEATH; + else + printk(KERN_ERR "Recursive die() failure, output suppressed\n"); + + bust_spinlocks(0); + die_lock_owner = -1; + spin_unlock_irq(&die_lock); do_exit(SIGSEGV); } Index: 11.7/include/asm-ia64/processor.h --- 11.7/include/asm-ia64/processor.h Thu, 11 Oct 2001 14:03:29 +1000 kaos (linux-2.4/s/49_processor. 1.1.3.2.2.1.1.4 644) +++ 11.7(w)/include/asm-ia64/processor.h Tue, 16 Oct 2001 12:28:13 +1000 kaos (linux-2.4/s/49_processor. 1.1.3.2.2.1.1.4 644) @@ -170,7 +170,6 @@ #define IA64_THREAD_KRBS_SYNCED (__IA64_UL(1) << 5) /* krbs synced with process vm? */ #define IA64_THREAD_FPEMU_NOPRINT (__IA64_UL(1) << 6) /* don't log any fpswa faults */ #define IA64_THREAD_FPEMU_SIGFPE (__IA64_UL(1) << 7) /* send a SIGFPE for fpswa faults */ -#define IA64_KERNEL_DEATH (__IA64_UL(1) << 63) /* see die_if_kernel()... */ #define IA64_THREAD_UAC_SHIFT 3 #define IA64_THREAD_UAC_MASK (IA64_THREAD_UAC_NOPRINT | IA64_THREAD_UAC_SIGBUS)