user/sven/linux.git/kernel/kcsan, branch v6.16.2

kcsan: test: Initialize dummy variable

2025-08-15T14:38:50Z

[ Upstream commit 9872916ad1a1a5e7d089e05166c85dbd65e5b0e8 ] Newer compiler versions rightfully point out: kernel/kcsan/kcsan_test.c:591:41: error: variable 'dummy' is uninitialized when passed as a const pointer argument here [-Werror,-Wuninitialized-const-pointer] 591 | KCSAN_EXPECT_READ_BARRIER(atomic_read(&dummy), false); | ^~~~~ 1 error generated. Although this particular test does not care about the value stored in the dummy atomic variable, let's silence the warning. Link: https://lkml.kernel.org/r/CA+G9fYu8JY=k-r0hnBRSkQQrFJ1Bz+ShdXNwC1TNeMt0eXaxeA@mail.gmail.com Fixes: 8bc32b348178 ("kcsan: test: Add test cases for memory barrier instrumentation") Reported-by: Linux Kernel Functional Testing Reviewed-by: Alexander Potapenko Signed-off-by: Marco Elver Signed-off-by: Sasha Levin

treewide, timers: Rename destroy_timer_on_stack() as timer_destroy_on_stack()

2025-05-08T17:49:33Z

Move this API to the canonical timer_*() namespace. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250507175338.672442-10-mingo@kernel.org

treewide: Switch/rename to timer_delete[_sync]()

2025-04-05T08:30:12Z

timer_delete[_sync]() replaces del_timer[_sync](). Convert the whole tree over and remove the historical wrapper inlines. Conversion was done with coccinelle plus manual fixups where necessary. Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar

kcsan: Remove redundant call of kallsyms_lookup_name()

2024-10-14T14:44:56Z

There is no need to repeatedly call kallsyms_lookup_name, we can reuse the return value of this function. Signed-off-by: Ran Xiaokai Signed-off-by: Marco Elver

kcsan: Turn report_filterlist_lock into a raw_spinlock

2024-10-14T14:44:48Z

Ran Xiaokai reports that with a KCSAN-enabled PREEMPT_RT kernel, we can see splats like: | BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 | in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1 | preempt_count: 10002, expected: 0 | RCU nest depth: 0, expected: 0 | no locks held by swapper/1/0. | irq event stamp: 156674 | hardirqs last enabled at (156673): [] do_idle+0x1f9/0x240 | hardirqs last disabled at (156674): [] sysvec_apic_timer_interrupt+0x14/0xc0 | softirqs last enabled at (0): [] copy_process+0xfc7/0x4b60 | softirqs last disabled at (0): [<0000000000000000>] 0x0 | Preemption disabled at: | [] paint_ptr+0x2a/0x90 | CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.11.0+ #3 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 | Call Trace: | | dump_stack_lvl+0x7e/0xc0 | dump_stack+0x1d/0x30 | __might_resched+0x1a2/0x270 | rt_spin_lock+0x68/0x170 | kcsan_skip_report_debugfs+0x43/0xe0 | print_report+0xb5/0x590 | kcsan_report_known_origin+0x1b1/0x1d0 | kcsan_setup_watchpoint+0x348/0x650 | __tsan_unaligned_write1+0x16d/0x1d0 | hrtimer_interrupt+0x3d6/0x430 | __sysvec_apic_timer_interrupt+0xe8/0x3a0 | sysvec_apic_timer_interrupt+0x97/0xc0 | On a detected data race, KCSAN's reporting logic checks if it should filter the report. That list is protected by the report_filterlist_lock *non-raw* spinlock which may sleep on RT kernels. Since KCSAN may report data races in any context, convert it to a raw_spinlock. This requires being careful about when to allocate memory for the filter list itself which can be done via KCSAN's debugfs interface. Concurrent modification of the filter list via debugfs should be rare: the chosen strategy is to optimistically pre-allocate memory before the critical section and discard if unused. Link: https://lore.kernel.org/all/20240925143154.2322926-1-ranxiaokai627@163.com/ Reported-by: Ran Xiaokai Tested-by: Ran Xiaokai Signed-off-by: Marco Elver

kcsan: Use min() to fix Coccinelle warning

2024-08-01T23:40:44Z

Fixes the following Coccinelle/coccicheck warning reported by minmax.cocci: WARNING opportunity for min() Use const size_t instead of int for the result of min(). Compile-tested with CONFIG_KCSAN=y. Reviewed-by: Marco Elver Signed-off-by: Thorsten Blum Signed-off-by: Paul E. McKenney

kcsan: Add missing MODULE_DESCRIPTION() macro

2024-06-06T18:21:14Z

Fix the warning reported by 'make C=1 W=1': WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/kcsan/kcsan_test.o Signed-off-by: Jeff Johnson Reviewed-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan, compiler_types: Introduce __data_racy type qualifier

2024-05-07T18:39:50Z

Based on the discussion at [1], it would be helpful to mark certain variables as explicitly "data racy", which would result in KCSAN not reporting data races involving any accesses on such variables. To do that, introduce the __data_racy type qualifier: struct foo { ... int __data_racy bar; ... }; In KCSAN-kernels, __data_racy turns into volatile, which KCSAN already treats specially by considering them "marked". In non-KCSAN kernels the type qualifier turns into no-op. The generated code between KCSAN-instrumented kernels and non-KCSAN kernels is already huge (inserted calls into runtime for every memory access), so the extra generated code (if any) due to volatile for few such __data_racy variables are unlikely to have measurable impact on performance. Link: https://lore.kernel.org/all/CAHk-=wi3iondeh_9V2g3Qz5oHTRjLsOpoy83hb58MVh=nRZe0A@mail.gmail.com/ [1] Suggested-by: Linus Torvalds Signed-off-by: Marco Elver Cc: Paul E. McKenney Cc: Tetsuo Handa Signed-off-by: Paul E. McKenney

mm: delete checks for xor_unlock_is_negative_byte()

2023-10-18T21:34:17Z

Architectures which don't define their own use the one in asm-generic/bitops/lock.h. Get rid of all the ifdefs around "maybe we don't have it". Link: https://lkml.kernel.org/r/20231004165317.1061855-15-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Geert Uytterhoeven Cc: Albert Ou Cc: Alexander Gordeev Cc: Andreas Dilger Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Heiko Carstens Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Richard Henderson Cc: Sven Schnelle Cc: "Theodore Ts'o" Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Signed-off-by: Andrew Morton

bitops: add xor_unlock_is_negative_byte()

2023-10-18T21:34:16Z

Replace clear_bit_and_unlock_is_negative_byte() with xor_unlock_is_negative_byte(). We have a few places that like to lock a folio, set a flag and unlock it again. Allow for the possibility of combining the latter two operations for efficiency. We are guaranteed that the caller holds the lock, so it is safe to unlock it with the xor. The caller must guarantee that nobody else will set the flag without holding the lock; it is not safe to do this with the PG_dirty flag, for example. Link: https://lkml.kernel.org/r/20231004165317.1061855-8-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Albert Ou Cc: Alexander Gordeev Cc: Andreas Dilger Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Geert Uytterhoeven Cc: Heiko Carstens Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Richard Henderson Cc: Sven Schnelle Cc: "Theodore Ts'o" Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Signed-off-by: Andrew Morton