From b0d65a8cbcb097d2110885c3660add97b0125867 Mon Sep 17 00:00:00 2001 From: Oliver O'Halloran Date: Fri, 7 Dec 2018 02:17:12 +1100 Subject: [PATCH] powerpc/papr_scm: Fix DIMM device registration race When a new nvdimm device is registered with libnvdimm via nvdimm_create() it is added as a device on the nvdimm bus. The probe function for the DIMM driver is potentially quite slow so actually registering and probing the device is done in an async domain rather than immediately after device creation. This can result in a race where the region device (created 2nd) is probed first and fails to activate at boot. To fix this we use the same approach as the ACPI/NFIT driver which is to check that all the DIMM devices registered successfully. LibNVDIMM provides the nvdimm_bus_count_dimms() function which synchronises with the async domain and verifies that the dimm was successfully registered with the bus. If either of these does not occur then we bail. Fixes: b5beae5e224f ("powerpc/pseries: Add driver for PAPR SCM regions") Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/pseries/papr_scm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c index 8b5153c55da6..7dc6a751cb4c 100644 --- a/arch/powerpc/platforms/pseries/papr_scm.c +++ b/arch/powerpc/platforms/pseries/papr_scm.c @@ -223,6 +223,9 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p) goto err; } + if (nvdimm_bus_check_dimm_count(p->bus, 1)) + goto err; + /* now add the region */ memset(&mapping, 0, sizeof(mapping)); -- 2.11.0