x86/resctrl: Remove lockdep annotation that triggers false positive

get_domain_from_cpu() walks a list of domains to find the one that
contains the specified CPU. This needs to be protected against races
with CPU hotplug when the list is modified. It has recently gained
a lockdep annotation to check this.

The lockdep annotation causes false positives when called via IPI as the
lock is held, but by another process. Remove it.

  [ bp: Refresh it ontop of x86/cache. ]

Fixes: fb700810d30b ("x86/resctrl: Separate arch and fs resctrl locks")
Reported-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/all/ZdUSwOM9UUNpw84Y@agluck-desk3

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 8a4ef4f5bddc8bd7ce0ce812576f61d3f76127d9..83e40341583e6fa655e0531f0e8a8480d8567ba8 100644 (file)
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -362,15 +362,6 @@ struct rdt_domain *get_domain_from_cpu(int cpu, struct rdt_resource *r)
 {
        struct rdt_domain *d;
 
-       /*
-        * Walking r->domains, ensure it can't race with cpuhp.
-        * Because this is called via IPI by rdt_ctrl_update(), assertions
-        * about locks this thread holds will lead to false positives. Check
-        * someone is holding the CPUs lock.
-        */
-       if (IS_ENABLED(CONFIG_HOTPLUG_CPU) && IS_ENABLED(CONFIG_LOCKDEP))
-               WARN_ON_ONCE(!lockdep_is_cpus_held());
-
        list_for_each_entry(d, &r->domains, list) {
                /* Find the domain that contains this CPU */
                if (cpumask_test_cpu(cpu, &d->cpu_mask))