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From b66dd21b19108b7846b07145ceeb5bf1dabdbf5a Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Fri, 3 Jul 2009 08:44:12 -0500
Subject: [PATCH] x86: Don't disable preemption in exception handlers without IST
commit 4c67d0b3e40f01c4b681994ac64bf8f83e6caad9 in tip.
Some of the exception handlers that run on an IST in a normal kernel
still disable preemption. This causes might_sleep warning when sending signals
for debugging in PREEMPT-RT because sending signals can take a lock.
Since the ISTs are disabled now for those don't disable the preemption.
This completes the remove IST patch I sent some time ago and fixes
another case where using gdb caused warnings.
Also it will likely improve latency a little bit.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
arch/x86/kernel/traps.c | 22 ++++++++++++----------
1 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 1168e44..ebba901 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -88,9 +88,10 @@ static inline void conditional_sti(struct pt_regs *regs)
local_irq_enable();
}
-static inline void preempt_conditional_sti(struct pt_regs *regs)
+static inline void preempt_conditional_sti(struct pt_regs *regs, int stack)
{
- inc_preempt_count();
+ if (stack)
+ inc_preempt_count();
if (regs->flags & X86_EFLAGS_IF)
local_irq_enable();
}
@@ -101,11 +102,12 @@ static inline void conditional_cli(struct pt_regs *regs)
local_irq_disable();
}
-static inline void preempt_conditional_cli(struct pt_regs *regs)
+static inline void preempt_conditional_cli(struct pt_regs *regs, int stack)
{
if (regs->flags & X86_EFLAGS_IF)
local_irq_disable();
- dec_preempt_count();
+ if (stack)
+ dec_preempt_count();
}
#ifdef CONFIG_X86_32
@@ -232,9 +234,9 @@ dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
12, SIGBUS) == NOTIFY_STOP)
return;
- preempt_conditional_sti(regs);
+ preempt_conditional_sti(regs, STACKFAULT_STACK);
do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
- preempt_conditional_cli(regs);
+ preempt_conditional_cli(regs, STACKFAULT_STACK);
}
dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
@@ -470,9 +472,9 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
return;
#endif
- preempt_conditional_sti(regs);
+ preempt_conditional_sti(regs, DEBUG_STACK);
do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
- preempt_conditional_cli(regs);
+ preempt_conditional_cli(regs, DEBUG_STACK);
}
#ifdef CONFIG_X86_64
@@ -557,7 +559,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
return;
/* It's safe to allow irq's after DR6 has been saved */
- preempt_conditional_sti(regs);
+ preempt_conditional_sti(regs, DEBUG_STACK);
if (regs->flags & X86_VM_MASK) {
handle_vm86_trap((struct kernel_vm86_regs *) regs,
@@ -580,7 +582,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
si_code = get_si_code(tsk->thread.debugreg6);
if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS))
send_sigtrap(tsk, regs, error_code, si_code);
- preempt_conditional_cli(regs);
+ preempt_conditional_cli(regs, DEBUG_STACK);
return;
}
--
1.7.0.4
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