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 --- drivers/md/dm-cache-background-tracker.h | 88 ++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 drivers/md/dm-cache-background-tracker.h (limited to 'drivers/md/dm-cache-background-tracker.h') diff --git a/drivers/md/dm-cache-background-tracker.h b/drivers/md/dm-cache-background-tracker.h new file mode 100644 index 000000000..47156c14a --- /dev/null +++ b/drivers/md/dm-cache-background-tracker.h @@ -0,0 +1,88 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2017 Red Hat. All rights reserved. + * + * This file is released under the GPL. + */ + +#ifndef DM_CACHE_BACKGROUND_WORK_H +#define DM_CACHE_BACKGROUND_WORK_H + +#include +#include "dm-cache-policy.h" + +/*----------------------------------------------------------------*/ + +/* + * The cache policy decides what background work should be performed, + * such as promotions, demotions and writebacks. The core cache target + * is in charge of performing the work, and does so when it sees fit. + * + * The background_tracker acts as a go between. Keeping track of future + * work that the policy has decided upon, and handing (issuing) it to + * the core target when requested. + * + * There is no locking in this, so calls will probably need to be + * protected with a spinlock. + */ + +struct bt_work { + struct list_head list; + struct rb_node node; + struct policy_work work; +}; + +extern struct kmem_cache *btracker_work_cache; + +struct background_work; +struct background_tracker; + +/* + * Create a new tracker, it will not be able to queue more than + * 'max_work' entries. + */ +struct background_tracker *btracker_create(unsigned int max_work); + +/* + * Destroy the tracker. No issued, but not complete, work should + * exist when this is called. It is fine to have queued but unissued + * work. + */ +void btracker_destroy(struct background_tracker *b); + +unsigned int btracker_nr_demotions_queued(struct background_tracker *b); + +/* + * Queue some work within the tracker. 'work' should point to the work + * to queue, this will be copied (ownership doesn't pass). If pwork + * is not NULL then it will be set to point to the tracker's internal + * copy of the work. + * + * returns -EINVAL iff the work is already queued. -ENOMEM if the work + * couldn't be queued for another reason. + */ +int btracker_queue(struct background_tracker *b, + struct policy_work *work, + struct policy_work **pwork); + +/* + * Hands out the next piece of work to be performed. + * Returns -ENODATA if there's no work. + */ +int btracker_issue(struct background_tracker *b, struct policy_work **work); + +/* + * Informs the tracker that the work has been completed and it may forget + * about it. + */ +void btracker_complete(struct background_tracker *b, struct policy_work *op); + +/* + * Predicate to see if an origin block is already scheduled for promotion. + */ +bool btracker_promotion_already_present(struct background_tracker *b, + dm_oblock_t oblock); + +/*----------------------------------------------------------------*/ + +#endif -- cgit v1.3.1