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Yusuke EndohandClaude Opus 5.5
053f8da910
Under the M:N thread scheduler, a Ruby thread in a non-main Ractor may be
resumed on a different native thread after it blocks. The C compiler
assumes that the native thread never changes within a function, so it may
compute the address of ruby_current_ec once (`__tls_get_addr` in
libruby.so) and reuse it after the switch. The address then refers to the
TLS of the previous native thread, which leads to a SEGV or to using
another thread's ec.
8.times.map do
Ractor.new do
50.times do
",,".split(/(,)/) { sleep 0.001 }
end
:ok
end
end.map(&:value)
#=> [BUG] Segmentation fault at 0x0000000000000030 (with Clang 21)
arm64 and ppc64le already use the out-of-line rb_current_ec()
(RB_THREAD_CURRENT_EC_NOINLINE), which prevents the compiler from caching
the address. Use it on all platforms, and remove the macro.
[Bug #22453]
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
#ifndef RUBY_THREAD_PTHREAD_H
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#define RUBY_THREAD_PTHREAD_H
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/**********************************************************************
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thread_pthread.h -
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$Author$
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Copyright (C) 2004-2007 Koichi Sasada
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This platform runs the common scheduler; see thread_sched.h for its data
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structures and thread_sched.c for the implementation.
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**********************************************************************/
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#ifdef HAVE_PTHREAD_NP_H
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#include <pthread_np.h>
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#endif
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#define RB_NATIVETHREAD_LOCK_INIT PTHREAD_MUTEX_INITIALIZER
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#define RB_NATIVETHREAD_COND_INIT PTHREAD_COND_INITIALIZER
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#include "thread_sched.h"
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#ifdef RB_THREAD_LOCAL_SPECIFIER
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NOINLINE(void rb_current_ec_set(struct rb_execution_context_struct *));
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// Under M:N threads, a thread may move to another native thread in the middle of
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// a C function, so the compiler must not cache the TLS address of ruby_current_ec.
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NOINLINE(struct rb_execution_context_struct *rb_current_ec(void));
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// for RUBY_DEBUG_LOG()
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RUBY_EXTERN RB_THREAD_LOCAL_SPECIFIER rb_atomic_t ruby_nt_serial;
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#define RUBY_NT_SERIAL 1
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#else
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typedef pthread_key_t native_tls_key_t;
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static inline void *
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native_tls_get(native_tls_key_t key)
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{
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// return value should be checked by caller
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return pthread_getspecific(key);
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}
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static inline void
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native_tls_set(native_tls_key_t key, void *ptr)
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{
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if (UNLIKELY(pthread_setspecific(key, ptr) != 0)) {
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rb_bug("pthread_setspecific error");
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}
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}
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RUBY_EXTERN native_tls_key_t ruby_current_ec_key;
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#endif
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#endif /* RUBY_THREAD_PTHREAD_H */
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