ACPI / drivers: replace acpi_probe_lock spinlock with mutex
Commite647b53227
("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:e647b53227
(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>
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@ -2054,7 +2054,7 @@ int __init acpi_scan_init(void)
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static struct acpi_probe_entry *ape;
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static struct acpi_probe_entry *ape;
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static int acpi_probe_count;
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static int acpi_probe_count;
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static DEFINE_SPINLOCK(acpi_probe_lock);
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static DEFINE_MUTEX(acpi_probe_mutex);
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static int __init acpi_match_madt(struct acpi_subtable_header *header,
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static int __init acpi_match_madt(struct acpi_subtable_header *header,
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const unsigned long end)
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const unsigned long end)
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@ -2073,7 +2073,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
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if (acpi_disabled)
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if (acpi_disabled)
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return 0;
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return 0;
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spin_lock(&acpi_probe_lock);
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mutex_lock(&acpi_probe_mutex);
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for (ape = ap_head; nr; ape++, nr--) {
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for (ape = ap_head; nr; ape++, nr--) {
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if (ACPI_COMPARE_NAME(ACPI_SIG_MADT, ape->id)) {
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if (ACPI_COMPARE_NAME(ACPI_SIG_MADT, ape->id)) {
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acpi_probe_count = 0;
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acpi_probe_count = 0;
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@ -2086,7 +2086,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
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count++;
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count++;
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}
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}
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}
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}
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spin_unlock(&acpi_probe_lock);
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mutex_unlock(&acpi_probe_mutex);
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return count;
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return count;
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}
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}
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