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[Pal] Replace locks with atomics in Dk{Get,Set}ExceptionHandler()

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These functions are executed on signal-handling path and thus must
not contain any locking (otherwise nested signals will deadlock).
This commit is contained in:
Dmitrii Kuvaiskii
2020-06-10 07:10:44 +00:00
parent 052033df9d
commit 20ecea9bed
1 changed files with 3 additions and 31 deletions
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Pal/src/db_exception.c
+3 -31
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@@ -31,33 +31,10 @@
#include "pal_error.h"
#include "pal_internal.h"
#define INIT_EVENT_HANDLER { .lock = LOCK_INIT, .upcall = NULL }
struct pal_event_handler {
PAL_LOCK lock;
PAL_EVENT_HANDLER upcall;
};
struct pal_event_handler handlers[] = {
[0] = INIT_EVENT_HANDLER,
[PAL_EVENT_ARITHMETIC_ERROR] = INIT_EVENT_HANDLER,
[PAL_EVENT_MEMFAULT] = INIT_EVENT_HANDLER,
[PAL_EVENT_ILLEGAL] = INIT_EVENT_HANDLER,
[PAL_EVENT_QUIT] = INIT_EVENT_HANDLER,
[PAL_EVENT_SUSPEND] = INIT_EVENT_HANDLER,
[PAL_EVENT_RESUME] = INIT_EVENT_HANDLER,
[PAL_EVENT_FAILURE] = INIT_EVENT_HANDLER,
[PAL_EVENT_PIPE] = INIT_EVENT_HANDLER,
};
PAL_EVENT_HANDLER handlers[PAL_EVENT_NUM_BOUND] = { 0 };
PAL_EVENT_HANDLER _DkGetExceptionHandler(PAL_NUM event) {
struct pal_event_handler* eh = &handlers[event];
_DkInternalLock(&eh->lock);
PAL_EVENT_HANDLER upcall = eh->upcall;
_DkInternalUnlock(&eh->lock);
return upcall;
return __atomic_load_n(&handlers[event], __ATOMIC_ACQUIRE);
}
PAL_BOL
@@ -69,12 +46,7 @@ DkSetExceptionHandler(PAL_EVENT_HANDLER handler, PAL_NUM event) {
LEAVE_PAL_CALL_RETURN(PAL_FALSE);
}
struct pal_event_handler* eh = &handlers[event];
_DkInternalLock(&eh->lock);
eh->upcall = handler;
_DkInternalUnlock(&eh->lock);
__atomic_store_n(&handlers[event], handler, __ATOMIC_RELEASE);
LEAVE_PAL_CALL_RETURN(PAL_TRUE);
}