redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

powerpc/eeh: Only dump stack once if an MMIO loop is detected 

[ Upstream commit 4e0942c030 ]

Many drivers don't check for errors when they get a 0xFFs response from an
MMIO load. As a result after an EEH event occurs a driver can get stuck in
a polling loop unless it some kind of internal timeout logic.

Currently EEH tries to detect and report stuck drivers by dumping a stack
trace after eeh_dev_check_failure() is called EEH_MAX_FAILS times on an
already frozen PE. The value of EEH_MAX_FAILS was chosen so that a dump
would occur every few seconds if the driver was spinning in a loop. This
results in a lot of spurious stack traces in the kernel log.

Fix this by limiting it to printing one stack trace for each PE freeze. If
the driver is truely stuck the kernel's hung task detector is better suited
to reporting the probelm anyway.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Sam Bobroff <sbobroff@linux.ibm.com>
Tested-by: Sam Bobroff <sbobroff@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191016012536.22588-1-oohall@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Oliver O'Halloran 2019-10-16 12:25:36 +11:00 committed by Greg Kroah-Hartman
parent fed639f7e1
commit 821bf0bf65
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/kernel/eeh.c
View File

@ -503,7 +503,7 @@ int eeh_dev_check_failure(struct eeh_dev *edev)
rc = 1;
if (pe->state & EEH_PE_ISOLATED) {
pe->check_count++;
if (pe->check_count % EEH_MAX_FAILS == 0) {
if (pe->check_count == EEH_MAX_FAILS) {
dn = pci_device_to_OF_node(dev);
if (dn)
location = of_get_property(dn, "ibm,loc-code",