From ed5c41d30ef2ce578fd6b6e2f7ec23f2a58b1eba Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 5 Aug 2014 22:57:19 +0200 Subject: [PATCH] x86: MCE: Add raw_lock conversion again Commit ea431643d6c3 ("x86/mce: Fix CMCI preemption bugs") breaks RT by the completely unrelated conversion of the cmci_discover_lock to a regular (non raw) spinlock. This lock was annotated in commit 59d958d2c7de ("locking, x86: mce: Annotate cmci_discover_lock as raw") with a proper explanation why. The argument for converting the lock back to a regular spinlock was: - it does percpu ops without disabling preemption. Preemption is not disabled due to the mistaken use of a raw spinlock. Which is complete nonsense. The raw_spinlock is disabling preemption in the same way as a regular spinlock. In mainline spinlock maps to raw_spinlock, in RT spinlock becomes a "sleeping" lock. raw_spinlock has on RT exactly the same semantics as in mainline. And because this lock is taken in non preemptible context it must be raw on RT. Undo the locking brainfart. Reported-by: Clark Williams Reported-by: Steven Rostedt Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds --- arch/x86/kernel/cpu/mcheck/mce_intel.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c index 9a316b21df8b..3bdb95ae8c43 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_intel.c +++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c @@ -42,7 +42,7 @@ static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned); * cmci_discover_lock protects against parallel discovery attempts * which could race against each other. */ -static DEFINE_SPINLOCK(cmci_discover_lock); +static DEFINE_RAW_SPINLOCK(cmci_discover_lock); #define CMCI_THRESHOLD 1 #define CMCI_POLL_INTERVAL (30 * HZ) @@ -144,14 +144,14 @@ static void cmci_storm_disable_banks(void) int bank; u64 val; - spin_lock_irqsave(&cmci_discover_lock, flags); + raw_spin_lock_irqsave(&cmci_discover_lock, flags); owned = __get_cpu_var(mce_banks_owned); for_each_set_bit(bank, owned, MAX_NR_BANKS) { rdmsrl(MSR_IA32_MCx_CTL2(bank), val); val &= ~MCI_CTL2_CMCI_EN; wrmsrl(MSR_IA32_MCx_CTL2(bank), val); } - spin_unlock_irqrestore(&cmci_discover_lock, flags); + raw_spin_unlock_irqrestore(&cmci_discover_lock, flags); } static bool cmci_storm_detect(void) @@ -211,7 +211,7 @@ static void cmci_discover(int banks) int i; int bios_wrong_thresh = 0; - spin_lock_irqsave(&cmci_discover_lock, flags); + raw_spin_lock_irqsave(&cmci_discover_lock, flags); for (i = 0; i < banks; i++) { u64 val; int bios_zero_thresh = 0; @@ -266,7 +266,7 @@ static void cmci_discover(int banks) WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks))); } } - spin_unlock_irqrestore(&cmci_discover_lock, flags); + raw_spin_unlock_irqrestore(&cmci_discover_lock, flags); if (mca_cfg.bios_cmci_threshold && bios_wrong_thresh) { pr_info_once( "bios_cmci_threshold: Some banks do not have valid thresholds set\n"); @@ -316,10 +316,10 @@ void cmci_clear(void) if (!cmci_supported(&banks)) return; - spin_lock_irqsave(&cmci_discover_lock, flags); + raw_spin_lock_irqsave(&cmci_discover_lock, flags); for (i = 0; i < banks; i++) __cmci_disable_bank(i); - spin_unlock_irqrestore(&cmci_discover_lock, flags); + raw_spin_unlock_irqrestore(&cmci_discover_lock, flags); } static void cmci_rediscover_work_func(void *arg) @@ -360,9 +360,9 @@ void cmci_disable_bank(int bank) if (!cmci_supported(&banks)) return; - spin_lock_irqsave(&cmci_discover_lock, flags); + raw_spin_lock_irqsave(&cmci_discover_lock, flags); __cmci_disable_bank(bank); - spin_unlock_irqrestore(&cmci_discover_lock, flags); + raw_spin_unlock_irqrestore(&cmci_discover_lock, flags); } static void intel_init_cmci(void) -- 2.20.1