bthread: use macros for safer thread-local access on ARM

[altman08]

Route accesses to tls_task_group, tls_task_group_nosignal, tls_bls and several mutex-profiling thread-locals (tls_inside_lock, tls_warn_up, tls_pthread_lock_count, tls_csites, tls_ever_created_keytable) through the BAIDU_(GET|SET|GET_PTR)_VOLATILE_THREAD_LOCAL macros instead of touching the raw __thread variables directly.

On aarch64/clang the compiler can incorrectly cache the address of a thread_local variable across a suspend point (e.g. when a bthread is rescheduled onto another worker), so raw accesses can silently read a stale TaskGroup*/LocalStorage. Going through the accessor macros everywhere forces a fresh, non-cached load/store on those platforms while staying a plain variable access elsewhere.

Add bthread::tls_bls_ptr() as the single helper for obtaining the current LocalStorage*, and update all call sites (bthread.cpp, butex.cpp, fd.cpp, key.cpp, mutex.cpp, task_control.cpp, brpc/controller.cpp, test/bthread_unittest.cpp) to use it instead of declaring their own stale/mistyped extern references to tls_task_group or tls_bls.

Also hardens borrow_keytable()/return_keytable() in key.cpp: the KeyTableList pointer obtained under the read lock is no longer reused after re-acquiring the write lock, since pool->list/pool->destroyed may change concurrently via bthread_keytable_pool_destroy(); the thread-local list is drained first before falling back to the pool's global free list.

What problem does this PR solve?

Issue Number: resolve

Problem Summary:

What is changed and the side effects?

Changed:

Side effects:

• Performance effects:

• Breaking backward compatibility:

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Check List:

• Please make sure your changes are compilable.
• When providing us with a new feature, it is best to add related tests.
• Please follow Contributor Covenant Code of Conduct.

[chenBright]

Use CHECK_EQ(g->tag(), tag) is more appropriate.

[altman08]

Use CHECK_EQ(g->tag(), tag) is more appropriate.

fixed

[Copilot]

Pull request overview

This PR strengthens bthread thread-local (TLS) correctness on aarch64/clang by routing accesses to key TLS variables through the BAIDU_(GET|SET|GET_PTR)_VOLATILE_THREAD_LOCAL accessors, and by consolidating access to LocalStorage via a single helper.

Changes:

• Add bthread::tls_bls_ptr() and migrate call sites away from direct __thread/raw TLS references.
• Convert multiple TLS variables (task group pointers, mutex profiling TLS flags/counters, etc.) to use volatile TLS macros and accessor calls.
• Harden keytable pool borrow/return logic to avoid reusing potentially stale pointers across lock upgrades.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/bthread_unittest.cpp	Updates span-related TLS access to use tls_bls_ptr()
src/bthread/task_meta.h	Introduces tls_bls_ptr() helper for LocalStorage TLS
src/bthread/task_group.cpp	Refactors LocalStorage cleanup to use tls_bls_ptr() helper
src/bthread/task_control.cpp	Routes tls_task_group initialization/reads through volatile TLS accessors
src/bthread/mutex.cpp	Converts contention-profiler TLS vars to volatile TLS macros/accessors
src/bthread/key.cpp	Removes raw TLS externs; uses tls_bls_ptr() and hardens keytable pool operations
src/bthread/fd.cpp	Uses volatile TLS accessors for tls_task_group
src/bthread/butex.cpp	Uses volatile TLS accessors for tls_task_group comparisons/reads
src/bthread/bthread.cpp	Converts tls_task_group_nosignal to volatile TLS and updates access patterns
src/brpc/span.h	Removes raw TLS extern declaration from header
src/brpc/controller.cpp	Uses volatile TLS accessors for retry backoff logic

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[wwbmmm]

Why add this?

[altman08]

CHECK_EQ(g->tag(), tag);

Why add this?

I added CHECK_EQ(g->tag(), tag) and removed this line.