x86/mce: Kill drain_mcelog_buffer()

This used to flush out MCEs logged during early boot and which
were in the MCA registers from a previous system run. No need
for that now, since we've moved to a genpool.

Suggested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1439396985-12812-7-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/mce.h

@@ -140,7 +140,7 @@ struct mce_vendor_flags {
 extern struct mce_vendor_flags mce_flags;
 
 extern struct mca_config mca_cfg;
-extern void mce_register_decode_chain(struct notifier_block *nb, bool drain);
+extern void mce_register_decode_chain(struct notifier_block *nb);
 extern void mce_unregister_decode_chain(struct notifier_block *nb);
 
 #include <linux/percpu.h>

arch/x86/kernel/cpu/mcheck/mce.c

@@ -199,55 +199,15 @@ void mce_log(struct mce *mce)
 	set_bit(0, &mce_need_notify);
 }
 
-static void drain_mcelog_buffer(void)
-{
-	unsigned int next, i, prev = 0;
-
-	next = ACCESS_ONCE(mcelog.next);
-
-	do {
-		struct mce *m;
-
-		/* drain what was logged during boot */
-		for (i = prev; i < next; i++) {
-			unsigned long start = jiffies;
-			unsigned retries = 1;
-
-			m = &mcelog.entry[i];
-
-			while (!m->finished) {
-				if (time_after_eq(jiffies, start + 2*retries))
-					retries++;
-
-				cpu_relax();
-
-				if (!m->finished && retries >= 4) {
-					pr_err("skipping error being logged currently!\n");
-					break;
-				}
-			}
-			smp_rmb();
-			atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m);
-		}
-
-		memset(mcelog.entry + prev, 0, (next - prev) * sizeof(*m));
-		prev = next;
-		next = cmpxchg(&mcelog.next, prev, 0);
-	} while (next != prev);
-}
-
 static struct notifier_block mce_srao_nb;
 
-void mce_register_decode_chain(struct notifier_block *nb, bool drain)
+void mce_register_decode_chain(struct notifier_block *nb)
 {
 	/* Ensure SRAO notifier has the highest priority in the decode chain. */
 	if (nb != &mce_srao_nb && nb->priority == INT_MAX)
 		nb->priority -= 1;
 
 	atomic_notifier_chain_register(&x86_mce_decoder_chain, nb);
-
-	if (drain)
-		drain_mcelog_buffer();
 }
 EXPORT_SYMBOL_GPL(mce_register_decode_chain);
 
@@ -2028,7 +1988,7 @@ __setup("mce", mcheck_enable);
 int __init mcheck_init(void)
 {
 	mcheck_intel_therm_init();
-	mce_register_decode_chain(&mce_srao_nb, false);
+	mce_register_decode_chain(&mce_srao_nb);
 	mcheck_vendor_init_severity();
 
 	INIT_WORK(&mce_work, mce_process_work);

drivers/acpi/acpi_extlog.c

@@ -286,7 +286,7 @@ static int __init extlog_init(void)
 	 */
 	old_edac_report_status = get_edac_report_status();
 	set_edac_report_status(EDAC_REPORTING_DISABLED);
-	mce_register_decode_chain(&extlog_mce_dec, true);
+	mce_register_decode_chain(&extlog_mce_dec);
 	/* enable OS to be involved to take over management from BIOS */
 	((struct extlog_l1_head *)extlog_l1_addr)->flags |= FLAG_OS_OPTIN;
 

drivers/edac/i7core_edac.c

@@ -2424,7 +2424,7 @@ static int __init i7core_init(void)
 	pci_rc = pci_register_driver(&i7core_driver);
 
 	if (pci_rc >= 0) {
-		mce_register_decode_chain(&i7_mce_dec, true);
+		mce_register_decode_chain(&i7_mce_dec);
 		return 0;
 	}
 

drivers/edac/mce_amd.c

@@ -895,7 +895,7 @@ static int __init mce_amd_init(void)
 
 	pr_info("MCE: In-kernel MCE decoding enabled.\n");
 
-	mce_register_decode_chain(&amd_mce_dec_nb, true);
+	mce_register_decode_chain(&amd_mce_dec_nb);
 
 	return 0;
 }

drivers/edac/sb_edac.c

@@ -2591,7 +2591,7 @@ static int __init sbridge_init(void)
 
 	pci_rc = pci_register_driver(&sbridge_driver);
 	if (pci_rc >= 0) {
-		mce_register_decode_chain(&sbridge_mce_dec, true);
+		mce_register_decode_chain(&sbridge_mce_dec);
 		if (get_edac_report_status() == EDAC_REPORTING_DISABLED)
 			sbridge_printk(KERN_WARNING, "Loading driver, error reporting disabled.\n");
 		return 0;