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authorRussell Currey <ruscur@russell.cc>2023-08-23 08:53:17 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2023-08-24 15:33:17 +0300
commiteac030b22ea12cdfcbb2e941c21c03964403c63f (patch)
tree6e20ff95a5a5b8588b87160065d9a0d5b836a5a2 /drivers/cpuidle
parent1aa000667669fa855853decbb1c69e974d8ff716 (diff)
downloadlinux-eac030b22ea12cdfcbb2e941c21c03964403c63f.tar.xz
powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT
lppaca_shared_proc() takes a pointer to the lppaca which is typically accessed through get_lppaca(). With DEBUG_PREEMPT enabled, this leads to checking if preemption is enabled, for example: BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693 caller is lparcfg_data+0x408/0x19a0 CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2 Call Trace: dump_stack_lvl+0x154/0x200 (unreliable) check_preemption_disabled+0x214/0x220 lparcfg_data+0x408/0x19a0 ... This isn't actually a problem however, as it does not matter which lppaca is accessed, the shared proc state will be the same. vcpudispatch_stats_procfs_init() already works around this by disabling preemption, but the lparcfg code does not, erroring any time /proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled. Instead of disabling preemption on the caller side, rework lppaca_shared_proc() to not take a pointer and instead directly access the lppaca, bypassing any potential preemption checks. Fixes: f13c13a00512 ("powerpc: Stop using non-architected shared_proc field in lppaca") Signed-off-by: Russell Currey <ruscur@russell.cc> [mpe: Rework to avoid needing a definition in paca.h and lppaca.h] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230823055317.751786-4-mpe@ellerman.id.au
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/cpuidle-pseries.c8
1 files changed, 1 insertions, 7 deletions
diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c
index a7d33f3ee01e..14db9b7d985d 100644
--- a/drivers/cpuidle/cpuidle-pseries.c
+++ b/drivers/cpuidle/cpuidle-pseries.c
@@ -414,13 +414,7 @@ static int __init pseries_idle_probe(void)
return -ENODEV;
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
- /*
- * Use local_paca instead of get_lppaca() since
- * preemption is not disabled, and it is not required in
- * fact, since lppaca_ptr does not need to be the value
- * associated to the current CPU, it can be from any CPU.
- */
- if (lppaca_shared_proc(local_paca->lppaca_ptr)) {
+ if (lppaca_shared_proc()) {
cpuidle_state_table = shared_states;
max_idle_state = ARRAY_SIZE(shared_states);
} else {