Merge tag 'pm+acpi-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management and ACPI updates from Rafael Wysocki:
 "The rework of backlight interface selection API from Hans de Goede
  stands out from the number of commits and the number of affected
  places perspective.  The cpufreq core fixes from Viresh Kumar are
  quite significant too as far as the number of commits goes and because
  they should reduce CPU online/offline overhead quite a bit in the
  majority of cases.

  From the new featues point of view, the ACPICA update (to upstream
  revision 20150515) adding support for new ACPI 6 material to ACPICA is
  the one that matters the most as some new significant features will be
  based on it going forward.  Also included is an update of the ACPI
  device power management core to follow ACPI 6 (which in turn reflects
  the Windows' device PM implementation), a PM core extension to support
  wakeup interrupts in a more generic way and support for the ACPI _CCA
  device configuration object.

  The rest is mostly fixes and cleanups all over and some documentation
  updates, including new DT bindings for Operating Performance Points.

  There is one fix for a regression introduced in the 4.1 cycle, but it
  adds quite a number of lines of code, it wasn't really ready before
  Thursday and you were on vacation, so I refrained from pushing it on
  the last minute for 4.1.

  Specifics:

   - ACPICA update to upstream revision 20150515 including basic support
     for ACPI 6 features: new ACPI tables introduced by ACPI 6 (STAO,
     XENV, WPBT, NFIT, IORT), changes related to the other tables (DTRM,
     FADT, LPIT, MADT), new predefined names (_BTH, _CR3, _DSD, _LPI,
     _MTL, _PRR, _RDI, _RST, _TFP, _TSN), fixes and cleanups (Bob Moore,
     Lv Zheng).

   - ACPI device power management core code update to follow ACPI 6
     which reflects the ACPI device power management implementation in
     Windows (Rafael J Wysocki).

   - rework of the backlight interface selection logic to reduce the
     number of kernel command line options and improve the handling of
     DMI quirks that may be involved in that and to make the code
     generally more straightforward (Hans de Goede).

   - fixes for the ACPI Embedded Controller (EC) driver related to the
     handling of EC transactions (Lv Zheng).

   - fix for a regression related to the ACPI resources management and
     resulting from a recent change of ACPI initialization code ordering
     (Rafael J Wysocki).

   - fix for a system initialization regression related to ACPI
     introduced during the 3.14 cycle and caused by running the code
     that switches the platform over to the ACPI mode too early in the
     initialization sequence (Rafael J Wysocki).

   - support for the ACPI _CCA device configuration object related to
     DMA cache coherence (Suravee Suthikulpanit).

   - ACPI/APEI fixes and cleanups (Jiri Kosina, Borislav Petkov).

   - ACPI battery driver cleanups (Luis Henriques, Mathias Krause).

   - ACPI processor driver cleanups (Hanjun Guo).

   - cleanups and documentation update related to the ACPI device
     properties interface based on _DSD (Rafael J Wysocki).

   - ACPI device power management fixes (Rafael J Wysocki).

   - assorted cleanups related to ACPI (Dominik Brodowski, Fabian
     Frederick, Lorenzo Pieralisi, Mathias Krause, Rafael J Wysocki).

   - fix for a long-standing issue causing General Protection Faults to
     be generated occasionally on return to user space after resume from
     ACPI-based suspend-to-RAM on 32-bit x86 (Ingo Molnar).

   - fix to make the suspend core code return -EBUSY consistently in all
     cases when system suspend is aborted due to wakeup detection (Ruchi
     Kandoi).

   - support for automated device wakeup IRQ handling allowing drivers
     to make their PM support more starightforward (Tony Lindgren).

   - new tracepoints for suspend-to-idle tracing and rework of the
     prepare/complete callbacks tracing in the PM core (Todd E Brandt,
     Rafael J Wysocki).

   - wakeup sources framework enhancements (Jin Qian).

   - new macro for noirq system PM callbacks (Grygorii Strashko).

   - assorted cleanups related to system suspend (Rafael J Wysocki).

   - cpuidle core cleanups to make the code more efficient (Rafael J
     Wysocki).

   - powernv/pseries cpuidle driver update (Shilpasri G Bhat).

   - cpufreq core fixes related to CPU online/offline that should reduce
     the overhead of these operations quite a bit, unless the CPU in
     question is physically going away (Viresh Kumar, Saravana Kannan).

   - serialization of cpufreq governor callbacks to avoid race
     conditions in some cases (Viresh Kumar).

   - intel_pstate driver fixes and cleanups (Doug Smythies, Prarit
     Bhargava, Joe Konno).

   - cpufreq driver (arm_big_little, cpufreq-dt, qoriq) updates (Sudeep
     Holla, Felipe Balbi, Tang Yuantian).

   - assorted cleanups in cpufreq drivers and core (Shailendra Verma,
     Fabian Frederick, Wang Long).

   - new Device Tree bindings for representing Operating Performance
     Points (Viresh Kumar).

   - updates for the common clock operations support code in the PM core
     (Rajendra Nayak, Geert Uytterhoeven).

   - PM domains core code update (Geert Uytterhoeven).

   - Intel Knights Landing support for the RAPL (Running Average Power
     Limit) power capping driver (Dasaratharaman Chandramouli).

   - fixes related to the floor frequency setting on Atom SoCs in the
     RAPL power capping driver (Ajay Thomas).

   - runtime PM framework documentation update (Ben Dooks).

   - cpupower tool fix (Herton R Krzesinski)"

* tag 'pm+acpi-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (194 commits)
  cpuidle: powernv/pseries: Auto-promotion of snooze to deeper idle state
  x86: Load __USER_DS into DS/ES after resume
  PM / OPP: Add binding for 'opp-suspend'
  PM / OPP: Allow multiple OPP tables to be passed via DT
  PM / OPP: Add new bindings to address shortcomings of existing bindings
  ACPI: Constify ACPI device IDs in documentation
  ACPI / enumeration: Document the rules regarding the PRP0001 device ID
  ACPI / video: Make acpi_video_unregister_backlight() private
  acpi-video-detect: Remove old API
  toshiba-acpi: Port to new backlight interface selection API
  thinkpad-acpi: Port to new backlight interface selection API
  sony-laptop: Port to new backlight interface selection API
  samsung-laptop: Port to new backlight interface selection API
  msi-wmi: Port to new backlight interface selection API
  msi-laptop: Port to new backlight interface selection API
  intel-oaktrail: Port to new backlight interface selection API
  ideapad-laptop: Port to new backlight interface selection API
  fujitsu-laptop: Port to new backlight interface selection API
  eeepc-laptop: Port to new backlight interface selection API
  dell-wmi: Port to new backlight interface selection API
  ...

1 files changed, 55 insertions, 53 deletions

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index e82d0976a5d0..2bfd53cbfe80 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -729,10 +729,10 @@ static struct llist_head ghes_estatus_llist;
 static struct irq_work ghes_proc_irq_work;
 
 /*
- * NMI may be triggered on any CPU, so ghes_nmi_lock is used for
- * mutual exclusion.
+ * NMI may be triggered on any CPU, so ghes_in_nmi is used for
+ * having only one concurrent reader.
  */
-static DEFINE_RAW_SPINLOCK(ghes_nmi_lock);
+static atomic_t ghes_in_nmi = ATOMIC_INIT(0);
 
 static LIST_HEAD(ghes_nmi);
 
@@ -797,73 +797,75 @@ static void ghes_print_queued_estatus(void)
         }
 }
 
+/* Save estatus for further processing in IRQ context */
+static void __process_error(struct ghes *ghes)
+{
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+        u32 len, node_len;
+        struct ghes_estatus_node *estatus_node;
+        struct acpi_hest_generic_status *estatus;
+
+        if (ghes_estatus_cached(ghes->estatus))
+                return;
+
+        len = cper_estatus_len(ghes->estatus);
+        node_len = GHES_ESTATUS_NODE_LEN(len);
+
+        estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, node_len);
+        if (!estatus_node)
+                return;
+
+        estatus_node->ghes = ghes;
+        estatus_node->generic = ghes->generic;
+        estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
+        memcpy(estatus, ghes->estatus, len);
+        llist_add(&estatus_node->llnode, &ghes_estatus_llist);
+#endif
+}
+
+static void __ghes_panic(struct ghes *ghes)
+{
+        oops_begin();
+        ghes_print_queued_estatus();
+        __ghes_print_estatus(KERN_EMERG, ghes->generic, ghes->estatus);
+
+        /* reboot to log the error! */
+        if (panic_timeout == 0)
+                panic_timeout = ghes_panic_timeout;
+        panic("Fatal hardware error!");
+}
+
 static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
 {
-        struct ghes *ghes, *ghes_global = NULL;
-        int sev, sev_global = -1;
-        int ret = NMI_DONE;
+        struct ghes *ghes;
+        int sev, ret = NMI_DONE;
+
+        if (!atomic_add_unless(&ghes_in_nmi, 1, 1))
+                return ret;
 
-        raw_spin_lock(&ghes_nmi_lock);
         list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
                 if (ghes_read_estatus(ghes, 1)) {
                         ghes_clear_estatus(ghes);
                         continue;
                 }
-                sev = ghes_severity(ghes->estatus->error_severity);
-                if (sev > sev_global) {
-                        sev_global = sev;
-                        ghes_global = ghes;
-                }
-                ret = NMI_HANDLED;
-        }
-
-        if (ret == NMI_DONE)
-                goto out;
 
-        if (sev_global >= GHES_SEV_PANIC) {
-                oops_begin();
-                ghes_print_queued_estatus();
-                __ghes_print_estatus(KERN_EMERG, ghes_global->generic,
-                                     ghes_global->estatus);
-                /* reboot to log the error! */
-                if (panic_timeout == 0)
-                        panic_timeout = ghes_panic_timeout;
-                panic("Fatal hardware error!");
-        }
+                sev = ghes_severity(ghes->estatus->error_severity);
+                if (sev >= GHES_SEV_PANIC)
+                        __ghes_panic(ghes);
 
-        list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
-#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
-                u32 len, node_len;
-                struct ghes_estatus_node *estatus_node;
-                struct acpi_hest_generic_status *estatus;
-#endif
                 if (!(ghes->flags & GHES_TO_CLEAR))
                         continue;
-#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
-                if (ghes_estatus_cached(ghes->estatus))
-                        goto next;
-                /* Save estatus for further processing in IRQ context */
-                len = cper_estatus_len(ghes->estatus);
-                node_len = GHES_ESTATUS_NODE_LEN(len);
-                estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool,
-                                                      node_len);
-                if (estatus_node) {
-                        estatus_node->ghes = ghes;
-                        estatus_node->generic = ghes->generic;
-                        estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
-                        memcpy(estatus, ghes->estatus, len);
-                        llist_add(&estatus_node->llnode, &ghes_estatus_llist);
-                }
-next:
-#endif
+
+                __process_error(ghes);
                 ghes_clear_estatus(ghes);
+
+                ret = NMI_HANDLED;
         }
+
 #ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
         irq_work_queue(&ghes_proc_irq_work);
 #endif
-
-out:
-        raw_spin_unlock(&ghes_nmi_lock);
+        atomic_dec(&ghes_in_nmi);
         return ret;
 }