linux-kernel - [PATCH] x86/mce: Remove mce_report

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Date:   Mon, 25 Mar 2019 18:21:21 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     linux-edac <linux-edac@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Tony Luck <tony.luck@...el.com>, x86@...nel.org
Subject: [PATCH] x86/mce: Remove mce_report_event()

From: Borislav Petkov <bp@...e.de>

Calling this function has been wrong for a while now:

* Can't call schedule_work() in #MC context.

* mce_notify_irq() either.

* None of that noodling is needed anymore - all it needs to do is kick
the IRQ work which would self-IPI so that once the #MC handler is done,
the work queue will run and process queued MCE records.

So remove it.

Reported-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Tony Luck <tony.luck@...el.com>
Cc: x86@...nel.org
---
 arch/x86/kernel/cpu/mce/core.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index b7fb541a4873..ca031fc79769 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -460,23 +460,6 @@ static void mce_irq_work_cb(struct irq_work *entry)
 	mce_schedule_work();
 }
 
-static void mce_report_event(struct pt_regs *regs)
-{
-	if (regs->flags & (X86_VM_MASK|X86_EFLAGS_IF)) {
-		mce_notify_irq();
-		/*
-		 * Triggering the work queue here is just an insurance
-		 * policy in case the syscall exit notify handler
-		 * doesn't run soon enough or ends up running on the
-		 * wrong CPU (can happen when audit sleeps)
-		 */
-		mce_schedule_work();
-		return;
-	}
-
-	irq_work_queue(&mce_irq_work);
-}
-
 /*
  * Check if the address reported by the CPU is in a format we can parse.
  * It would be possible to add code for most other cases, but all would
@@ -1301,7 +1284,8 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 		mce_panic("Fatal machine check on current CPU", &m, msg);
 
 	if (worst > 0)
-		mce_report_event(regs);
+		irq_work_queue(&mce_irq_work);
+
 	mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
 
 	sync_core();
-- 
2.21.0