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https://github.com/bytecodealliance/wasm-micro-runtime.git
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444b159963
Send a signal whose handler is no-op to a blocking thread to wake up the blocking syscall with either EINTR equivalent or partial success. Unlike the approach taken in the `dev/interrupt_block_insn` branch (that is, signal + longjmp similarly to `OS_ENABLE_HW_BOUND_CHECK`), this PR does not use longjmp because: * longjmp from signal handler doesn't work on nuttx refer to https://github.com/apache/nuttx/issues/10326 * the singal+longjmp approach may be too difficult for average programmers who might implement host functions to deal with See also https://github.com/bytecodealliance/wasm-micro-runtime/issues/1910
93 lines
2.3 KiB
C
93 lines
2.3 KiB
C
/*
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* Copyright (C) 2023 Midokura Japan KK. All rights reserved.
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* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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*/
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#include "wasm_runtime_common.h"
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#include "bh_platform.h"
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#include "bh_common.h"
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#include "bh_assert.h"
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#if WASM_ENABLE_THREAD_MGR != 0 && defined(OS_ENABLE_WAKEUP_BLOCKING_OP)
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#define LOCK(env) WASM_SUSPEND_FLAGS_LOCK((env)->wait_lock)
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#define UNLOCK(env) WASM_SUSPEND_FLAGS_UNLOCK((env)->wait_lock)
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#define ISSET(env, bit) \
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((WASM_SUSPEND_FLAGS_GET((env)->suspend_flags) & WASM_SUSPEND_FLAG_##bit) \
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!= 0)
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#define SET(env, bit) \
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WASM_SUSPEND_FLAGS_FETCH_OR((env)->suspend_flags, WASM_SUSPEND_FLAG_##bit)
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#define CLR(env, bit) \
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WASM_SUSPEND_FLAGS_FETCH_AND((env)->suspend_flags, ~WASM_SUSPEND_FLAG_##bit)
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bool
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wasm_runtime_begin_blocking_op(wasm_exec_env_t env)
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{
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LOCK(env);
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bh_assert(!ISSET(env, BLOCKING));
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SET(env, BLOCKING);
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if (ISSET(env, TERMINATE)) {
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CLR(env, BLOCKING);
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UNLOCK(env);
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return false;
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}
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UNLOCK(env);
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os_begin_blocking_op();
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return true;
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}
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void
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wasm_runtime_end_blocking_op(wasm_exec_env_t env)
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{
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int saved_errno = errno;
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LOCK(env);
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bh_assert(ISSET(env, BLOCKING));
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CLR(env, BLOCKING);
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UNLOCK(env);
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os_end_blocking_op();
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errno = saved_errno;
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}
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void
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wasm_runtime_interrupt_blocking_op(wasm_exec_env_t env)
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{
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/*
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* ISSET(BLOCKING) here means that the target thread
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* is in somewhere between wasm_begin_blocking_op and
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* wasm_end_blocking_op.
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* keep waking it up until it reaches wasm_end_blocking_op,
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* which clears the BLOCKING bit.
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*
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* this dumb loop is necessary because posix doesn't provide
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* a way to unmask signal and block atomically.
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*/
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LOCK(env);
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SET(env, TERMINATE);
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while (ISSET(env, BLOCKING)) {
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UNLOCK(env);
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os_wakeup_blocking_op(env->handle);
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/* relax a bit */
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os_usleep(50 * 1000);
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LOCK(env);
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}
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UNLOCK(env);
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}
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#else /* WASM_ENABLE_THREAD_MGR && OS_ENABLE_WAKEUP_BLOCKING_OP */
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bool
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wasm_runtime_begin_blocking_op(wasm_exec_env_t env)
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{
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return true;
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}
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void
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wasm_runtime_end_blocking_op(wasm_exec_env_t env)
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{}
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#endif /* WASM_ENABLE_THREAD_MGR && OS_ENABLE_WAKEUP_BLOCKING_OP */
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