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CommandQueueMT: Fix race conditions

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This commit is contained in:
Pedro J. Estébanez 2025-11-11 13:05:42 +01:00
parent b79fe2e020
commit b16a8b8a76
1 changed files with 19 additions and 5 deletions
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24
core/templates/command_queue_mt.h
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@ -39,6 +39,8 @@
#include "core/typedefs.h"
class CommandQueueMT {
static const size_t MAX_COMMAND_SIZE = 1024;
struct CommandBase {
bool sync = false;
virtual void call() = 0;
@ -154,19 +156,28 @@ class CommandQueueMT {
}
void _flush() {
MutexLock lock(mutex);
if (unlikely(flush_read_ptr)) {
// Re-entrant call.
return;
}
MutexLock lock(mutex);
char cmd_backup[MAX_COMMAND_SIZE];
while (flush_read_ptr < command_mem.size()) {
uint64_t size = *(uint64_t *)&command_mem[flush_read_ptr];
flush_read_ptr += 8;
flush_read_ptr += sizeof(uint64_t);
CommandBase *cmd = reinterpret_cast<CommandBase *>(&command_mem[flush_read_ptr]);
// Protect against race condition between this thread
// during the call to the command and other threads potentially
// invalidating the pointer due to reallocs.
memcpy(cmd_backup, (char *)cmd, size);
uint32_t allowance_id = WorkerThreadPool::thread_enter_unlock_allowance_zone(lock);
cmd->call();
((CommandBase *)cmd_backup)->call();
WorkerThreadPool::thread_exit_unlock_allowance_zone(allowance_id);
// Handle potential realloc due to the command and unlock allowance.
@ -174,9 +185,9 @@ class CommandQueueMT {
if (unlikely(cmd->sync)) {
sync_head++;
lock.~MutexLock(); // Give an opportunity to awaiters right away.
lock.temp_unlock(); // Give an opportunity to awaiters right away.
sync_cond_var.notify_all();
new (&lock) MutexLock(mutex);
lock.temp_relock();
// Handle potential realloc happened during unlock.
cmd = reinterpret_cast<CommandBase *>(&command_mem[flush_read_ptr]);
}
@ -210,6 +221,7 @@ public:
void push(T *p_instance, M p_method, Args &&...p_args) {
// Standard command, no sync.
using CommandType = Command<T, M, false, Args...>;
static_assert(sizeof(CommandType) <= MAX_COMMAND_SIZE);
_push_internal<CommandType, false>(p_instance, p_method, std::forward<Args>(p_args)...);
}
@ -217,6 +229,7 @@ public:
void push_and_sync(T *p_instance, M p_method, Args... p_args) {
// Standard command, sync.
using CommandType = Command<T, M, true, Args...>;
static_assert(sizeof(CommandType) <= MAX_COMMAND_SIZE);
_push_internal<CommandType, true>(p_instance, p_method, std::forward<Args>(p_args)...);
}
@ -224,6 +237,7 @@ public:
void push_and_ret(T *p_instance, M p_method, R *r_ret, Args... p_args) {
// Command with return value, sync.
using CommandType = CommandRet<T, M, R, Args...>;
static_assert(sizeof(CommandType) <= MAX_COMMAND_SIZE);
_push_internal<CommandType, true>(p_instance, p_method, r_ret, std::forward<Args>(p_args)...);
}