Commit-ID: 07d495dae20717b00881798ef812f7aa53ca0eb3
Gitweb: http://git.kernel.org/tip/07d495dae20717b00881798ef812f7aa53ca0eb3
Author: Alexander Kuleshov <kuleshovmail@xxxxxxxxx>
AuthorDate: Mon, 28 Nov 2016 13:50:57 +0600
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sat, 4 Feb 2017 09:36:59 +0100
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@xxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Jianyu Zhan <nasa4836@xxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Link: http://lkml.kernel.org/r/20161128075057.7724-1-kuleshovmail@xxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/traps.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index bf0c6d0..1dc86ee 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -563,11 +563,9 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
* as we may switch to the interrupt stack.
*/
debug_stack_usage_inc();
- preempt_disable();
cond_local_irq_enable(regs);
do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
cond_local_irq_disable(regs);
- preempt_enable_no_resched();
debug_stack_usage_dec();
exit:
ist_exit(regs);
@@ -742,14 +740,12 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
debug_stack_usage_inc();
/* It's safe to allow irq's after DR6 has been saved */
- preempt_disable();
cond_local_irq_enable(regs);
if (v8086_mode(regs)) {
handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
X86_TRAP_DB);
cond_local_irq_disable(regs);
- preempt_enable_no_resched();
debug_stack_usage_dec();
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)
send_sigtrap(tsk, regs, error_code, si_code);
cond_local_irq_disable(regs);
- preempt_enable_no_resched();
debug_stack_usage_dec();
exit:
--
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