[PATCH v7 11/25] ACPI / APEI: Move NOTIFY_SEA between the estatus-queue and NOTIFY_NMI

James Morse
2018-12-03T18:07:17Z

The estatus-queue code is currently hidden by the NOTIFY_NMI #ifdefs.
Once NOTIFY_SEA starts using the estatus-queue we can stop hiding
it as each architecture has a user that can't be turned off.

Split the existing CONFIG_HAVE_ACPI_APEI_NMI block in two, and move
the SEA code into the gap.

This patch moves code around ... and changes the stale comment
describing why the status queue is necessary: printk() is no
longer the issue, its the helpers like memory_failure_queue() that
aren't nmi safe.

Signed-off-by: James Morse <james.morse@arm.com>
---
drivers/acpi/apei/ghes.c | 113 ++++++++++++++++++++-------------------
1 file changed, 59 insertions(+), 54 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 15d94373ba72..00fe4785e469 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -765,66 +765,21 @@ static struct notifier_block ghes_notifier_hed = {
.notifier_call = ghes_notify_hed,
};

-#ifdef CONFIG_ACPI_APEI_SEA
-static LIST_HEAD(ghes_sea);
-
-/*
- * Return 0 only if one of the SEA error sources successfully reported an error
- * record sent from the firmware.
- */
-int ghes_notify_sea(void)
-{
- struct ghes *ghes;
- int ret = -ENOENT;
-
- rcu_read_lock();
- list_for_each_entry_rcu(ghes, &ghes_sea, list) {
- if (!ghes_proc(ghes))
- ret = 0;
- }
- rcu_read_unlock();
- return ret;
-}
-
-static void ghes_sea_add(struct ghes *ghes)
-{
- mutex_lock(&ghes_list_mutex);
- list_add_rcu(&ghes->list, &ghes_sea);
- mutex_unlock(&ghes_list_mutex);
-}
-
-static void ghes_sea_remove(struct ghes *ghes)
-{
- mutex_lock(&ghes_list_mutex);
- list_del_rcu(&ghes->list);
- mutex_unlock(&ghes_list_mutex);
- synchronize_rcu();
-}
-#else /* CONFIG_ACPI_APEI_SEA */
-static inline void ghes_sea_add(struct ghes *ghes) { }
-static inline void ghes_sea_remove(struct ghes *ghes) { }
-#endif /* CONFIG_ACPI_APEI_SEA */
-
#ifdef CONFIG_HAVE_ACPI_APEI_NMI
/*
- * printk is not safe in NMI context. So in NMI handler, we allocate
- * required memory from lock-less memory allocator
- * (ghes_estatus_pool), save estatus into it, put them into lock-less
- * list (ghes_estatus_llist), then delay printk into IRQ context via
- * irq_work (ghes_proc_irq_work). ghes_estatus_size_request record
- * required pool size by all NMI error source.
+ * Handlers for CPER records may not be NMI safe. For example,
+ * memory_failure_queue() takes spinlocks and calls schedule_work_on().
+ * In any NMI-like handler, memory from ghes_estatus_pool is used to save
+ * estatus, and added to the ghes_estatus_llist. irq_work_queue() causes
+ * ghes_proc_in_irq() to run in IRQ context where each estatus in
+ * ghes_estatus_llist is processed.
+ *
+ * Memory from the ghes_estatus_pool is also used with the ghes_estatus_cache
+ * to suppress frequent messages.
*/
static struct llist_head ghes_estatus_llist;
static struct irq_work ghes_proc_irq_work;

-/*
- * NMI may be triggered on any CPU, so ghes_in_nmi is used for
- * having only one concurrent reader.
- */
-static atomic_t ghes_in_nmi = ATOMIC_INIT(0);
-
-static LIST_HEAD(ghes_nmi);
-
static void ghes_proc_in_irq(struct irq_work *irq_work)
{
struct llist_node *llnode, *next;
@@ -950,6 +905,56 @@ static int ghes_estatus_queue_notified(struct list_head *rcu_list)

return ret;
}
+#endif /* CONFIG_HAVE_ACPI_APEI_NMI */
+
+#ifdef CONFIG_ACPI_APEI_SEA
+static LIST_HEAD(ghes_sea);
+
+/*
+ * Return 0 only if one of the SEA error sources successfully reported an error
+ * record sent from the firmware.
+ */
+int ghes_notify_sea(void)
+{
+ struct ghes *ghes;
+ int ret = -ENOENT;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(ghes, &ghes_sea, list) {
+ if (!ghes_proc(ghes))
+ ret = 0;
+ }
+ rcu_read_unlock();
+ return ret;
+}
+
+static void ghes_sea_add(struct ghes *ghes)
+{
+ mutex_lock(&ghes_list_mutex);
+ list_add_rcu(&ghes->list, &ghes_sea);
+ mutex_unlock(&ghes_list_mutex);
+}
+
+static void ghes_sea_remove(struct ghes *ghes)
+{
+ mutex_lock(&ghes_list_mutex);
+ list_del_rcu(&ghes->list);
+ mutex_unlock(&ghes_list_mutex);
+ synchronize_rcu();
+}
+#else /* CONFIG_ACPI_APEI_SEA */
+static inline void ghes_sea_add(struct ghes *ghes) { }
+static inline void ghes_sea_remove(struct ghes *ghes) { }
+#endif /* CONFIG_ACPI_APEI_SEA */
+
+#ifdef CONFIG_HAVE_ACPI_APEI_NMI
+/*
+ * NMI may be triggered on any CPU, so ghes_in_nmi is used for
+ * having only one concurrent reader.
+ */
+static atomic_t ghes_in_nmi = ATOMIC_INIT(0);
+
+static LIST_HEAD(ghes_nmi);

static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
{
--
2.19.2