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Commit da68933e authored by Andrew Morton's avatar Andrew Morton Committed by Andi Kleen
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[PATCH] x86-64: dump_trace() atomicity fix 



Fix

BUG: using smp_processor_id() in preemptible [00000001] code:

in backtracer on preemptible debug kernels.

Cc: Andi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent bb0d977e

arch/x86_64/kernel/traps.c

+5 −3
Original line number Original line Diff line number Diff line
@@ -254,7 +254,7 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs, 
		unsigned long *stack,

		unsigned long *stack,

		struct stacktrace_ops *ops, void *data)

		struct stacktrace_ops *ops, void *data)

{

{

	const unsigned cpu = smp_processor_id();

	const unsigned cpu = get_cpu();

	unsigned long *irqstack_end = (unsigned long*)cpu_pda(cpu)->irqstackptr;

	unsigned long *irqstack_end = (unsigned long*)cpu_pda(cpu)->irqstackptr;

	unsigned used = 0;

	unsigned used = 0;

	struct thread_info *tinfo;

	struct thread_info *tinfo;
@@ -286,11 +286,11 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs, 
					MSG("Leftover inexact backtrace:");

					MSG("Leftover inexact backtrace:");

					stack = (unsigned long *)UNW_SP(&info);

					stack = (unsigned long *)UNW_SP(&info);

					if (!stack)

					if (!stack)

						return;

						goto out;

				} else

				} else

					MSG("Full inexact backtrace again:");

					MSG("Full inexact backtrace again:");

			} else if (call_trace >= 1)

			} else if (call_trace >= 1)

				return;

				goto out;

			else

			else

				MSG("Full inexact backtrace again:");

				MSG("Full inexact backtrace again:");

		} else

		} else
@@ -385,6 +385,8 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs, 
	tinfo = current_thread_info();

	tinfo = current_thread_info();

	HANDLE_STACK (valid_stack_ptr(tinfo, stack));

	HANDLE_STACK (valid_stack_ptr(tinfo, stack));

#undef HANDLE_STACK

#undef HANDLE_STACK

out:

	put_cpu();

}

}

EXPORT_SYMBOL(dump_trace);

EXPORT_SYMBOL(dump_trace);