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Locking: forcefully unwinding locks to a previously stored state

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Maria Matejka 2024-04-03 09:45:40 +02:00
parent 6806aacf74
commit d6ec3eaee4
1 changed files with 48 additions and 0 deletions
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48
lib/locking.h
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@ -81,6 +81,54 @@ extern DOMAIN(the_bird) the_bird_domain;
#define ASSERT_THE_BIRD_LOCKED ({ if (!the_bird_locked()) bug("The BIRD lock must be locked here: %s:%d", __FILE__, __LINE__); })
/* Unwind stored lock state helpers */
struct locking_unwind_status {
struct lock_order *desired;
enum {
LOCKING_UNWIND_SAME,
LOCKING_UNWIND_UNLOCK,
} state;
};
static inline struct locking_unwind_status locking_unwind_helper(struct locking_unwind_status status, uint order)
{
struct domain_generic **lsp = ((void *) &locking_stack) + order;
struct domain_generic **dp = ((void *) status.desired) + order;
if (!status.state)
{
/* Just checking that the rest of the stack is consistent */
if (*lsp != *dp)
bug("Mangled lock unwind state at order %d", order);
}
else if (*dp)
/* Stored state expects locked */
if (*lsp == *dp)
/* Indeed is locked, switch to check mode */
status.state = 0;
else
/* Not locked or locked elsewhere */
bug("Mangled lock unwind state at order %d", order);
else if (*lsp)
/* Stored state expects unlocked but we're locked */
DG_UNLOCK(*lsp);
return status;
}
static inline void locking_unwind(struct lock_order *desired)
{
struct locking_unwind_status status = {
.desired = desired,
.state = LOCKING_UNWIND_UNLOCK,
};
#define LOCK_ORDER_POS_HELPER(x) DOMAIN_ORDER(x),
#define LOCK_ORDER_POS MACRO_FOREACH(LOCK_ORDER_POS_HELPER, LOCK_ORDER)
MACRO_RPACK(locking_unwind_helper, status, LOCK_ORDER_POS);
#undef LOCK_ORDER_POS_HELPER
}
/**
* Objects bound with domains
*