diff options
| author | Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> | 2016-08-16 16:59:53 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-09-07 08:34:55 +0200 |
| commit | 04790a5d92b5827082b8159e8a0202354c147a3d (patch) | |
| tree | 647894d1e9df6aa9393d67633654b851fa2f699c | |
| parent | aeeae06593de55a83a90a833a0b394702d7021e5 (diff) | |
| download | lwn-04790a5d92b5827082b8159e8a0202354c147a3d.tar.gz lwn-04790a5d92b5827082b8159e8a0202354c147a3d.zip | |
ACPI / drivers: replace acpi_probe_lock spinlock with mutex
commit 5331d9cab32ef640b4cd38a43b0858874fbb7168 upstream.
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)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/acpi/scan.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index 5f28cf778349..f3c022292586 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -1967,7 +1967,7 @@ 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) @@ -1986,7 +1986,7 @@ 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--) { if (ACPI_COMPARE_NAME(ACPI_SIG_MADT, ape->id)) { acpi_probe_count = 0; @@ -1999,7 +1999,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr) count++; } } - spin_unlock(&acpi_probe_lock); + mutex_unlock(&acpi_probe_mutex); return count; } |