From 5331d9cab32ef640b4cd38a43b0858874fbb7168 Mon Sep 17 00:00:00 2001 From: Lorenzo Pieralisi Date: Tue, 16 Aug 2016 16:59:53 +0100 Subject: 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 Fixes: e647b532275b (ACPI: Add early device probing infrastructure) Cc: 4.4+ # 4.4+ Signed-off-by: Rafael J. Wysocki --- drivers/acpi/scan.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/acpi') 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--) { if (ACPI_COMPARE_NAME(ACPI_SIG_MADT, ape->id)) { acpi_probe_count = 0; @@ -2086,7 +2086,7 @@ 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; } -- cgit v1.2.3