diff options
authorLorenzo Pieralisi <lorenzo.pieralisi@arm.com>2016-08-16 16:59:53 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-09-02 22:22:21 +0200
commit5331d9cab32ef640b4cd38a43b0858874fbb7168 (patch)
parent3feab13c919f99b0a17d0ca22ae00cf90f5d3fd1 (diff)
ACPI / drivers: replace acpi_probe_lock spinlock with mutex
Commit e647b532275b ("ACPI: Add early device probing infrastructure") introduced code that allows inserting driver specific struct acpi_probe_entry probe entries into ACPI linker sections (one per-subsystem, eg irqchip, clocksource) that are then walked to retrieve the data and function hooks required to probe the respective kernel components. Probing for all entries in a section is triggered through the __acpi_probe_device_table() function, that in turn, according to the table ID a given probe entry reports parses the table with the function retrieved from the respective section structures (ie struct acpi_probe_entry). Owing to the current ACPI table parsing implementation, the __acpi_probe_device_table() function has to share global variables with the acpi_match_madt() function, so in order to guarantee mutual exclusion locking is required between the two functions. Current kernel code implements the locking through the acpi_probe_lock spinlock; this has the side effect of requiring all code called within the lock (ie struct acpi_probe_entry.probe_{table/subtbl} hooks) not to sleep. However, kernel subsystems that make use of the early probing infrastructure are relying on kernel APIs that may sleep (eg irq_domain_alloc_fwnode(), among others) in the function calls pointed at by struct acpi_probe_entry.{probe_table/subtbl} entries (eg gic_v2_acpi_init()), which is a bug. Since __acpi_probe_device_table() is called from context that is allowed to sleep the acpi_probe_lock spinlock can be replaced with a mutex; this fixes the issue whilst still guaranteeing mutual exclusion. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Fixes: e647b532275b (ACPI: Add early device probing infrastructure) Cc: 4.4+ <stable@vger.kernel.org> # 4.4+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index ad9fc84a8601..e878fc799af7 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2054,7 +2054,7 @@ int __init acpi_scan_init(void)
static struct acpi_probe_entry *ape;
static int acpi_probe_count;
-static DEFINE_SPINLOCK(acpi_probe_lock);
+static DEFINE_MUTEX(acpi_probe_mutex);
static int __init acpi_match_madt(struct acpi_subtable_header *header,
const unsigned long end)
@@ -2073,7 +2073,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
if (acpi_disabled)
return 0;
- spin_lock(&acpi_probe_lock);
+ mutex_lock(&acpi_probe_mutex);
for (ape = ap_head; nr; ape++, nr--) {
acpi_probe_count = 0;
@@ -2086,7 +2086,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
- spin_unlock(&acpi_probe_lock);
+ mutex_unlock(&acpi_probe_mutex);
return count;