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Commit 8a335a23 authored by Bob Moore's avatar Bob Moore Committed by Len Brown
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ACPICA: Fix AcpiWalkNamespace race condition with table unload 

Added a reader/writer locking mechanism to allow multiple
concurrent namespace walks (readers), but a dynamic table unload
will have exclusive access to the namespace. This fixes a problem
where a table unload could delete the portion of the namespace that
is currently being examined by a walk.  Adds a new file, utlock.c
that implements the reader/writer lock mechanism. ACPICA BZ 749.

http://www.acpica.org/bugzilla/show_bug.cgi?id=749



Signed-off-by: default avatarBob Moore <robert.moore@intel.com>
Signed-off-by: default avatarLin Ming <ming.m.lin@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent aab61b67

drivers/acpi/acpica/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -41,4 +41,4 @@ obj-y += tbxface.o tbinstal.o tbutils.o tbfind.o tbfadt.o tbxfroot.o 


obj-y += utalloc.o utdebug.o uteval.o utinit.o utmisc.o utxface.o \

		utcopy.o utdelete.o utglobal.o utmath.o utobject.o \

		utstate.o utmutex.o utobject.o utresrc.o
 
		utstate.o utmutex.o utobject.o utresrc.o utlock.o

drivers/acpi/acpica/acglobal.h

+4 −0
Original line number Diff line number Diff line
@@ -165,6 +165,10 @@ ACPI_EXTERN u8 acpi_gbl_integer_bit_width; 
ACPI_EXTERN u8 acpi_gbl_integer_byte_width;

ACPI_EXTERN u8 acpi_gbl_integer_nybble_width;



/* Reader/Writer lock is used for namespace walk and dynamic table unload */



ACPI_EXTERN struct acpi_rw_lock acpi_gbl_namespace_rw_lock;



/*****************************************************************************

 *

 * Mutual exlusion within ACPICA subsystem

drivers/acpi/acpica/aclocal.h

+8 −0
Original line number Diff line number Diff line
@@ -108,6 +108,14 @@ static char *acpi_gbl_mutex_names[ACPI_NUM_MUTEX] = { 
#endif

#endif



/* Lock structure for reader/writer interfaces */



struct acpi_rw_lock {

	acpi_mutex writer_mutex;

	acpi_mutex reader_mutex;

	u32 num_readers;

};



/*

 * Predefined handles for spinlocks used within the subsystem.

 * These spinlocks are created by acpi_ut_mutex_initialize

drivers/acpi/acpica/actables.h

+1 −1
Original line number Diff line number Diff line
@@ -79,7 +79,7 @@ void acpi_tb_delete_table(struct acpi_table_desc *table_desc); 


void acpi_tb_terminate(void);



void acpi_tb_delete_namespace_by_owner(u32 table_index);

acpi_status acpi_tb_delete_namespace_by_owner(u32 table_index);



acpi_status acpi_tb_allocate_owner_id(u32 table_index);

drivers/acpi/acpica/acutils.h

+15 −0
Original line number Diff line number Diff line
@@ -345,6 +345,21 @@ acpi_ut_execute_UID(struct acpi_namespace_node *device_node, 
acpi_status

acpi_ut_execute_sxds(struct acpi_namespace_node *device_node, u8 * highest);



/*

 * utlock - reader/writer locks

 */

acpi_status acpi_ut_create_rw_lock(struct acpi_rw_lock *lock);



void acpi_ut_delete_rw_lock(struct acpi_rw_lock *lock);



acpi_status acpi_ut_acquire_read_lock(struct acpi_rw_lock *lock);



acpi_status acpi_ut_release_read_lock(struct acpi_rw_lock *lock);



acpi_status acpi_ut_acquire_write_lock(struct acpi_rw_lock *lock);



void acpi_ut_release_write_lock(struct acpi_rw_lock *lock);



/*

 * utobject - internal object create/delete/cache routines

 */