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EDAC, i7core: 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 i7core_mce_check_error() is called.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/29ab2c370915c6e132fc5d88e7b72cb834bedbfe.1461855008.git.tony.luck@intel.com
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Tony Luck 2016-04-28 07:52:11 -07:00 committed by Borislav Petkov
parent de0336b30d
commit 5359534505
1 changed files with 5 additions and 76 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
drivers/edac/i7core_edac.c
View File

@ -271,16 +271,6 @@ struct i7core_pvt {
bool is_registered, enable_scrub;
/* 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;
/* DCLK Frequency used for computing scrub rate */
int dclk_freq;
@ -1792,56 +1782,15 @@ static void i7core_mce_output_error(struct mem_ctl_info *mci,
* i7core_check_error Retrieve and process errors reported by the
* hardware. Called by the Core module.
*/
static void i7core_check_error(struct mem_ctl_info *mci)
static void i7core_check_error(struct mem_ctl_info *mci, struct mce *m)
{
struct i7core_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
* losing an error.
*/
smp_rmb();
count = (pvt->mce_out + MCE_LOG_LEN - pvt->mce_in)
% MCE_LOG_LEN;
if (!count)
goto check_ce_error;
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) {
i7core_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++)
i7core_mce_output_error(mci, &pvt->mce_outentry[i]);
i7core_mce_output_error(mci, m);
/*
* Now, let's increment CE error counts
*/
check_ce_error:
if (!pvt->is_registered)
i7core_udimm_check_mc_ecc_err(mci);
else
@ -1849,12 +1798,8 @@ check_ce_error:
}
/*
* i7core_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 i7core_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 i7core_mce_check_error(struct notifier_block *nb, unsigned long val,
void *data)
@ -1882,21 +1827,7 @@ static int i7core_mce_check_error(struct notifier_block *nb, unsigned long val,
if (mce->bank != 8)
return NOTIFY_DONE;
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)
i7core_check_error(mci);
i7core_check_error(mci, mce);
/* Advise mcelog that the errors were handled */
return NOTIFY_STOP;
@ -2243,8 +2174,6 @@ static int i7core_register_mci(struct i7core_dev *i7core_dev)
get_dimm_config(mci);
/* record ptr to the generic device */
mci->pdev = &i7core_dev->pdev[0]->dev;
/* Set the function pointer to an actual operation function */
mci->edac_check = i7core_check_error;
/* Enable scrubrate setting */
if (pvt->enable_scrub)