From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- fs/jffs2/background.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100644 fs/jffs2/background.c (limited to 'fs/jffs2/background.c') diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c new file mode 100644 index 000000000..bb0ee1a59 --- /dev/null +++ b/fs/jffs2/background.c @@ -0,0 +1,165 @@ +/* + * JFFS2 -- Journalling Flash File System, Version 2. + * + * Copyright © 2001-2007 Red Hat, Inc. + * Copyright © 2004-2010 David Woodhouse + * + * Created by David Woodhouse + * + * For licensing information, see the file 'LICENCE' in this directory. + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include "nodelist.h" + + +static int jffs2_garbage_collect_thread(void *); + +void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c) +{ + assert_spin_locked(&c->erase_completion_lock); + if (c->gc_task && jffs2_thread_should_wake(c)) + send_sig(SIGHUP, c->gc_task, 1); +} + +/* This must only ever be called when no GC thread is currently running */ +int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c) +{ + struct task_struct *tsk; + int ret = 0; + + BUG_ON(c->gc_task); + + init_completion(&c->gc_thread_start); + init_completion(&c->gc_thread_exit); + + tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index); + if (IS_ERR(tsk)) { + pr_warn("fork failed for JFFS2 garbage collect thread: %pe\n", + tsk); + complete(&c->gc_thread_exit); + ret = PTR_ERR(tsk); + } else { + /* Wait for it... */ + jffs2_dbg(1, "Garbage collect thread is pid %d\n", tsk->pid); + wait_for_completion(&c->gc_thread_start); + ret = tsk->pid; + } + + return ret; +} + +void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c) +{ + int wait = 0; + spin_lock(&c->erase_completion_lock); + if (c->gc_task) { + jffs2_dbg(1, "Killing GC task %d\n", c->gc_task->pid); + send_sig(SIGKILL, c->gc_task, 1); + wait = 1; + } + spin_unlock(&c->erase_completion_lock); + if (wait) + wait_for_completion(&c->gc_thread_exit); +} + +static int jffs2_garbage_collect_thread(void *_c) +{ + struct jffs2_sb_info *c = _c; + sigset_t hupmask; + + siginitset(&hupmask, sigmask(SIGHUP)); + allow_signal(SIGKILL); + allow_signal(SIGSTOP); + allow_signal(SIGHUP); + + c->gc_task = current; + complete(&c->gc_thread_start); + + set_user_nice(current, 10); + + set_freezable(); + for (;;) { + sigprocmask(SIG_UNBLOCK, &hupmask, NULL); + again: + spin_lock(&c->erase_completion_lock); + if (!jffs2_thread_should_wake(c)) { + set_current_state (TASK_INTERRUPTIBLE); + spin_unlock(&c->erase_completion_lock); + jffs2_dbg(1, "%s(): sleeping...\n", __func__); + schedule(); + } else { + spin_unlock(&c->erase_completion_lock); + } + /* Problem - immediately after bootup, the GCD spends a lot + * of time in places like jffs2_kill_fragtree(); so much so + * that userspace processes (like gdm and X) are starved + * despite plenty of cond_resched()s and renicing. Yield() + * doesn't help, either (presumably because userspace and GCD + * are generally competing for a higher latency resource - + * disk). + * This forces the GCD to slow the hell down. Pulling an + * inode in with read_inode() is much preferable to having + * the GC thread get there first. */ + schedule_timeout_interruptible(msecs_to_jiffies(50)); + + if (kthread_should_stop()) { + jffs2_dbg(1, "%s(): kthread_stop() called\n", __func__); + goto die; + } + + /* Put_super will send a SIGKILL and then wait on the sem. + */ + while (signal_pending(current) || freezing(current)) { + unsigned long signr; + + if (try_to_freeze()) + goto again; + + signr = kernel_dequeue_signal(); + + switch(signr) { + case SIGSTOP: + jffs2_dbg(1, "%s(): SIGSTOP received\n", + __func__); + kernel_signal_stop(); + break; + + case SIGKILL: + jffs2_dbg(1, "%s(): SIGKILL received\n", + __func__); + goto die; + + case SIGHUP: + jffs2_dbg(1, "%s(): SIGHUP received\n", + __func__); + break; + default: + jffs2_dbg(1, "%s(): signal %ld received\n", + __func__, signr); + } + } + /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ + sigprocmask(SIG_BLOCK, &hupmask, NULL); + + jffs2_dbg(1, "%s(): pass\n", __func__); + if (jffs2_garbage_collect_pass(c) == -ENOSPC) { + pr_notice("No space for garbage collection. Aborting GC thread\n"); + goto die; + } + } + die: + spin_lock(&c->erase_completion_lock); + c->gc_task = NULL; + spin_unlock(&c->erase_completion_lock); + kthread_complete_and_exit(&c->gc_thread_exit, 0); +} -- cgit v1.3.1