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EDAC, sb_edac: Remove double buffering of error records 

In the bad old days the functions from x86_mce_decoder_chain could be
called in machine check context. So we used to carefully copy them and
defer processing until later. But in

  f29a7aff4b ("x86/mce: Avoid potential deadlock due to printk() in MCE context")

we switched the logging code to save the record in a genpool, and call
the functions that registered to be notified later from a work queue.

So drop all the double buffering and do all the work we want to do as
soon as sbridge_mce_check_error() is called.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Aristeu Rozanski <arozansk@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: patrickg@supermicro.com
Link: http://lkml.kernel.org/r/100025611cd780d9bca72792b2b2146760da53e0.1460756761.git.tony.luck@intel.com
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Tony Luck 2016-04-15 14:50:32 -07:00 committed by Borislav Petkov
parent ab67b6c22d
commit ad08c4e974
1 changed files with 3 additions and 85 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

88
drivers/edac/sb_edac.c
View File

@ -363,16 +363,6 @@ struct sbridge_pvt {
/* Memory type detection */
bool is_mirrored, is_lockstep, is_close_pg;
/* Fifo double buffers */
struct mce mce_entry[MCE_LOG_LEN];
struct mce mce_outentry[MCE_LOG_LEN];
/* Fifo in/out counters */
unsigned mce_in, mce_out;
/* Count indicator to show errors not got */
unsigned mce_overrun;
/* Memory description */
u64 tolm, tohm;
struct knl_pvt knl;
@ -3075,63 +3065,8 @@ static void sbridge_mce_output_error(struct mem_ctl_info *mci,
}
/*
* sbridge_check_error Retrieve and process errors reported by the
* hardware. Called by the Core module.
*/
static void sbridge_check_error(struct mem_ctl_info *mci)
{
struct sbridge_pvt *pvt = mci->pvt_info;
int i;
unsigned count = 0;
struct mce *m;
/*
* MCE first step: Copy all mce errors into a temporary buffer
* We use a double buffering here, to reduce the risk of
* loosing an error.
*/
smp_rmb();
count = (pvt->mce_out + MCE_LOG_LEN - pvt->mce_in)
% MCE_LOG_LEN;
if (!count)
return;
m = pvt->mce_outentry;
if (pvt->mce_in + count > MCE_LOG_LEN) {
unsigned l = MCE_LOG_LEN - pvt->mce_in;
memcpy(m, &pvt->mce_entry[pvt->mce_in], sizeof(*m) * l);
smp_wmb();
pvt->mce_in = 0;
count -= l;
m += l;
}
memcpy(m, &pvt->mce_entry[pvt->mce_in], sizeof(*m) * count);
smp_wmb();
pvt->mce_in += count;
smp_rmb();
if (pvt->mce_overrun) {
sbridge_printk(KERN_ERR, "Lost %d memory errors\n",
pvt->mce_overrun);
smp_wmb();
pvt->mce_overrun = 0;
}
/*
* MCE second step: parse errors and display
*/
for (i = 0; i < count; i++)
sbridge_mce_output_error(mci, &pvt->mce_outentry[i]);
}
/*
* sbridge_mce_check_error Replicates mcelog routine to get errors
* This routine simply queues mcelog errors, and
* return. The error itself should be handled later
* by sbridge_check_error.
* WARNING: As this routine should be called at NMI time, extra care should
* be taken to avoid deadlocks, and to be as fast as possible.
* Check that logging is enabled and that this is the right type
* of error for us to handle.
*/
static int sbridge_mce_check_error(struct notifier_block *nb, unsigned long val,
void *data)
@ -3176,21 +3111,7 @@ static int sbridge_mce_check_error(struct notifier_block *nb, unsigned long val,
"%u APIC %x\n", mce->cpuvendor, mce->cpuid,
mce->time, mce->socketid, mce->apicid);
smp_rmb();
if ((pvt->mce_out + 1) % MCE_LOG_LEN == pvt->mce_in) {
smp_wmb();
pvt->mce_overrun++;
return NOTIFY_DONE;
}
/* Copy memory error at the ringbuffer */
memcpy(&pvt->mce_entry[pvt->mce_out], mce, sizeof(*mce));
smp_wmb();
pvt->mce_out = (pvt->mce_out + 1) % MCE_LOG_LEN;
/* Handle fatal errors immediately */
if (mce->mcgstatus & 1)
sbridge_check_error(mci);
sbridge_mce_output_error(mci, mce);
/* Advice mcelog that the error were handled */
return NOTIFY_STOP;
@ -3276,9 +3197,6 @@ static int sbridge_register_mci(struct sbridge_dev *sbridge_dev, enum type type)
mci->dev_name = pci_name(pdev);
mci->ctl_page_to_phys = NULL;
/* Set the function pointer to an actual operation function */
mci->edac_check = sbridge_check_error;
pvt->info.type = type;
switch (type) {
case IVY_BRIDGE: