diff options
Diffstat (limited to 'gcc/ada/s-taprop.ads')
| -rw-r--r-- | gcc/ada/s-taprop.ads | 63 |
1 files changed, 39 insertions, 24 deletions
diff --git a/gcc/ada/s-taprop.ads b/gcc/ada/s-taprop.ads index df22279..c9171c6 100644 --- a/gcc/ada/s-taprop.ads +++ b/gcc/ada/s-taprop.ads @@ -29,8 +29,7 @@ -- covered by the GNU Public License. -- -- -- -- GNARL was developed by the GNARL team at Florida State University. It is -- --- now maintained by Ada Core Technologies Inc. in cooperation with Florida -- --- State University (http://www.gnat.com). -- +-- now maintained by Ada Core Technologies, Inc. (http://www.gnat.com). -- -- -- ------------------------------------------------------------------------------ @@ -138,9 +137,7 @@ package System.Task_Primitives.Operations is type Lock_Level is (PO_Level, Global_Task_Level, - All_Attrs_Level, - All_Tasks_Level, - Interrupts_Level, + RTS_Lock_Level, ATCB_Level); -- Type used to describe kind of lock for second form of Initialize_Lock -- call specified below. @@ -176,7 +173,7 @@ package System.Task_Primitives.Operations is -- corresponding Initialize_Lock operation. procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean); - procedure Write_Lock (L : access RTS_Lock); + procedure Write_Lock (L : access RTS_Lock; Global_Lock : Boolean := False); procedure Write_Lock (T : ST.Task_ID); pragma Inline (Write_Lock); -- Lock a lock object for write access. After this operation returns, @@ -190,6 +187,9 @@ package System.Task_Primitives.Operations is -- operation failed, which will happen if there is a priority ceiling -- violation. -- + -- For the operation on RTS_Lock, Global_Lock should be set to True + -- if L is a global lock (Single_RTS_Lock, Global_Task_Lock). + -- -- For the operation on ST.Task_ID, the lock is the special lock object -- associated with that task's ATCB. This lock has effective ceiling -- priority high enough that it is safe to call by a task with any @@ -221,7 +221,7 @@ package System.Task_Primitives.Operations is -- locking that make a reader-writer distinction have higher overhead. procedure Unlock (L : access Lock); - procedure Unlock (L : access RTS_Lock); + procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False); procedure Unlock (T : ST.Task_ID); pragma Inline (Unlock); -- Unlock a locked lock object. @@ -232,9 +232,12 @@ package System.Task_Primitives.Operations is -- read or write permission. (That is, matching pairs of Lock and Unlock -- operations on each lock object must be properly nested.) + -- For the operation on RTS_Lock, Global_Lock should be set to True + -- if L is a global lock (Single_RTS_Lock, Global_Task_Lock). + -- -- Note that Write_Lock for RTS_Lock does not have an out-parameter. -- RTS_Locks are used in situations where we have not made provision - -- for recovery from ceiling violations. We do not expect them to + -- for recovery from ceiling violations. We do not expect them to -- occur inside the runtime system, because all RTS locks have ceiling -- Priority'Last. @@ -243,7 +246,7 @@ package System.Task_Primitives.Operations is -- executing in the Interrupt_Priority range. -- It is not clear what to do about ceiling violations due - -- to RTS calls done at interrupt priority. In general, it + -- to RTS calls done at interrupt priority. In general, it -- is not acceptable to give all RTS locks interrupt priority, -- since that whould give terrible performance on systems where -- this has the effect of masking hardware interrupts, though we @@ -255,7 +258,7 @@ package System.Task_Primitives.Operations is -- penalties. -- For POSIX systems, we considered just skipping setting a - -- priority ceiling on RTS locks. This would mean there is no + -- priority ceiling on RTS locks. This would mean there is no -- ceiling violation, but we would end up with priority inversions -- inside the runtime system, resulting in failure to satisfy the -- Ada priority rules, and possible missed validation tests. @@ -267,9 +270,9 @@ package System.Task_Primitives.Operations is -- This issue should be reconsidered whenever we get around to -- checking for calls to potentially blocking operations from - -- within protected operations. If we check for such calls and + -- within protected operations. If we check for such calls and -- catch them on entry to the OS, it may be that we can eliminate - -- the possibility of ceiling violations inside the RTS. For this + -- the possibility of ceiling violations inside the RTS. For this -- to work, we would have to forbid explicitly setting the priority -- of a task to anything in the Interrupt_Priority range, at least. -- We would also have to check that there are no RTS-lock operations @@ -278,7 +281,7 @@ package System.Task_Primitives.Operations is -- The latter approach seems to be the best, i.e. to check on entry -- to RTS calls that may need to use locks that the priority is not - -- in the interrupt range. If there are RTS operations that NEED to + -- in the interrupt range. If there are RTS operations that NEED to -- be called from interrupt handlers, those few RTS locks should then -- be converted to PO-type locks, with ceiling Interrupt_Priority'Last. @@ -325,9 +328,9 @@ package System.Task_Primitives.Operations is -- Returns the resolution of the underlying clock used to implement -- RT_Clock. - ------------------ - -- Extensions -- - ------------------ + ---------------- + -- Extensions -- + ---------------- -- Whoever calls either of the Sleep routines is responsible -- for checking for pending aborts before the call. @@ -389,6 +392,26 @@ package System.Task_Primitives.Operations is function Get_Thread_Id (T : ST.Task_ID) return OSI.Thread_Id; -- returns the thread id of the specified task. + ----------------------- + -- RTS Entrance/Exit -- + ----------------------- + + -- Following two routines are used for possible operations needed + -- to be setup/cleared upon entrance/exit of RTS while maintaining + -- a single thread of control in the RTS. Since we intend these + -- routines to be used for implementing the Single_Lock RTS, + -- Lock_RTS should follow the first Defer_Abortion operation + -- entering RTS. In the same fashion Unlock_RTS should preceed + -- the last Undefer_Abortion exiting RTS. + -- + -- These routines also replace the functions Lock/Unlock_All_Tasks_List + + procedure Lock_RTS; + -- Take the global RTS lock. + + procedure Unlock_RTS; + -- Release the global RTS lock. + -------------------- -- Stack Checking -- -------------------- @@ -465,12 +488,4 @@ package System.Task_Primitives.Operations is -- Such functionality is needed by gdb on some targets (e.g VxWorks) -- Return True is the operation is successful - procedure Lock_All_Tasks_List; - procedure Unlock_All_Tasks_List; - -- Lock/Unlock the All_Tasks_L lock which protects - -- System.Initialization.All_Tasks_List and Known_Tasks - -- ??? These routines were previousely in System.Tasking.Initialization - -- but were moved here to avoid dependency problems. That would be - -- nice to look at it some day and put it back in Initialization. - end System.Task_Primitives.Operations; |