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x86/traps: Get rid of unnecessary preempt_disable/preempt_enable_no_resched 

Exception handlers which may run on IST stack call ist_enter() at the start
of execution and ist_exit() in the end. ist_enter() disables preemption
unconditionally and ist_exit() enables it.

So the extra preempt_disable/enable() pairs nested inside the
ist_enter/exit() regions are pointless and can be removed.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Jianyu Zhan <nasa4836@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20161128075057.7724-1-kuleshovmail@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Alexander Kuleshov 2016-11-28 13:50:57 +06:00 committed by Thomas Gleixner
parent 68dee8e2f2
commit 07d495dae2
1 changed files with 0 additions and 5 deletions
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5
arch/x86/kernel/traps.c
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@ -563,11 +563,9 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
* as we may switch to the interrupt stack. * as we may switch to the interrupt stack.
*/ */
debug_stack_usage_inc(); debug_stack_usage_inc();
preempt_disable();
cond_local_irq_enable(regs); cond_local_irq_enable(regs);
do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL); do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
cond_local_irq_disable(regs); cond_local_irq_disable(regs);
preempt_enable_no_resched();
debug_stack_usage_dec(); debug_stack_usage_dec();
exit: exit:
ist_exit(regs); ist_exit(regs);
@ -742,14 +740,12 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
debug_stack_usage_inc(); debug_stack_usage_inc();
/* It's safe to allow irq's after DR6 has been saved */ /* It's safe to allow irq's after DR6 has been saved */
preempt_disable();
cond_local_irq_enable(regs); cond_local_irq_enable(regs);
if (v8086_mode(regs)) { if (v8086_mode(regs)) {
handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
X86_TRAP_DB); X86_TRAP_DB);
cond_local_irq_disable(regs); cond_local_irq_disable(regs);
preempt_enable_no_resched();
debug_stack_usage_dec(); debug_stack_usage_dec();
goto exit; goto exit;
} }
@ -769,7 +765,6 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp) if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
send_sigtrap(tsk, regs, error_code, si_code); send_sigtrap(tsk, regs, error_code, si_code);
cond_local_irq_disable(regs); cond_local_irq_disable(regs);
preempt_enable_no_resched();
debug_stack_usage_dec(); debug_stack_usage_dec();
exit: exit: