KCSAN reported hundreds of instances of data-races in ACPICA like this one: [ 6.994149] ================================================================== [ 6.994443] BUG: KCSAN: data-race in acpi_ut_status_exit / acpi_ut_trace [ 6.994795] write to 0xffffffffbae5a884 of 4 bytes by task 0 on cpu 2: [ 6.994944] acpi_ut_status_exit (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/utdebug.c:467) [ 6.994957] acpi_hw_register_read (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwregs.c:563) [ 6.994968] acpi_read_bit_register (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwxface.c:171) [ 6.994980] acpi_idle_bm_check (/home/marvin/linux/kernel/torvalds2/drivers/acpi/processor_idle.c:511) [ 6.994990] acpi_idle_enter_bm (/home/marvin/linux/kernel/torvalds2/drivers/acpi/processor_idle.c:644 (discriminator 1)) [ 6.995000] acpi_idle_enter (/home/marvin/linux/kernel/torvalds2/drivers/acpi/processor_idle.c:695) [ 6.995010] cpuidle_enter_state (/home/marvin/linux/kernel/torvalds2/drivers/cpuidle/cpuidle.c:267) [ 6.995019] cpuidle_enter (/home/marvin/linux/kernel/torvalds2/drivers/cpuidle/cpuidle.c:390) [ 6.995027] call_cpuidle (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:135) [ 6.995038] do_idle (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:219 /home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:282) [ 6.995046] cpu_startup_entry (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:378 (discriminator 1)) [ 6.995055] start_secondary (/home/marvin/linux/kernel/torvalds2/arch/x86/kernel/smpboot.c:210 /home/marvin/linux/kernel/torvalds2/arch/x86/kernel/smpboot.c:294) [ 6.995066] secondary_startup_64_no_verify (/home/marvin/linux/kernel/torvalds2/arch/x86/kernel/head_64.S:433) [ 6.995121] read to 0xffffffffbae5a884 of 4 bytes by task 0 on cpu 9: [ 6.995267] acpi_ut_trace (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/utdebug.c:263) [ 6.995279] acpi_hw_validate_io_request (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwvalid.c:101) [ 6.995291] acpi_hw_read_port (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwvalid.c:202) [ 6.995303] acpi_hw_read (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwregs.c:251) [ 6.995313] acpi_hw_register_read (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwregs.c:725 /home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwregs.c:499) [ 6.995325] acpi_read_bit_register (/home/marvin/linux/kernel/torvalds2/drivers/acpi/acpica/hwxface.c:171) [ 6.995336] acpi_idle_bm_check (/home/marvin/linux/kernel/torvalds2/drivers/acpi/processor_idle.c:511) [ 6.995346] acpi_idle_enter_bm (/home/marvin/linux/kernel/torvalds2/drivers/acpi/processor_idle.c:644 (discriminator 1)) [ 6.995356] acpi_idle_enter (/home/marvin/linux/kernel/torvalds2/drivers/acpi/processor_idle.c:695) [ 6.995366] cpuidle_enter_state (/home/marvin/linux/kernel/torvalds2/drivers/cpuidle/cpuidle.c:267) [ 6.995375] cpuidle_enter (/home/marvin/linux/kernel/torvalds2/drivers/cpuidle/cpuidle.c:390) [ 6.995383] call_cpuidle (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:135) [ 6.995394] do_idle (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:219 /home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:282) [ 6.995402] cpu_startup_entry (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:378 (discriminator 1)) [ 6.995411] start_secondary (/home/marvin/linux/kernel/torvalds2/arch/x86/kernel/smpboot.c:210 /home/marvin/linux/kernel/torvalds2/arch/x86/kernel/smpboot.c:294) [ 6.995422] secondary_startup_64_no_verify (/home/marvin/linux/kernel/torvalds2/arch/x86/kernel/head_64.S:433) [ 6.995476] value changed: 0x00000004 -> 0x00000002 [ 6.995629] Reported by Kernel Concurrency Sanitizer on: [ 6.995748] CPU: 9 PID: 0 Comm: swapper/9 Not tainted 6.6.0-rc2-kcsan-00003-g16819584c239-dirty #21 [ 6.995758] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023 [ 6.995765] ================================================================== Please find the complete list at: https://domac.alu.unizg.hr/~mtodorov/linux/patches/acpica_utdebug/acpi_ut_status_exit.log.xz A number of unprotected increments: acpi_gbl_nesting_level++; and conditional statements: if (acpi_gbl_nesting_level) { acpi_gbl_nesting_level--; } no longer work in SMP environment. Proper locking like spin_lock(&acpi_utdebug_lock); acpi_gbl_nesting_level++; spin_unlock(&acpi_utdebug_lock); and spin_lock(&acpi_utdebug_lock); if (acpi_gbl_nesting_level) { acpi_gbl_nesting_level--; } spin_unlock(&acpi_utdebug_lock); makes these data-races go away. Additionally, READ_ONCE() or WRITE_ONCE() is required with the global variable acpi_gbl_nesting_level to prevent unwanted read or write reordering or other funny stuff the optmisers do. The patch eliminates KCSAN BUG warnings. Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx> Fixes: 6be2d72b18649 ("ACPICA: Update for a few debug output statements") Fixes: bf9b448ef8430 ("ACPICA: Debug output: Do not emit function nesting level for kernel build.") Fixes: 6e875fa0480c1 ("ACPICA: Debugger: fix slight indentation issue") Fixes: ^1da177e4c3f4 ("Initial git repository build.") Cc: Jung-uk Kim <jkim@xxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Erik Kaneda <erik.kaneda@xxxxxxxxx> Cc: Bob Moore <robert.moore@xxxxxxxxx> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx> Cc: Len Brown <lenb@xxxxxxxxxx> Cc: linux-acpi@xxxxxxxxxxxxxxx Cc: acpica-devel@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx> Reported-by: kernel test robot <lkp@xxxxxxxxx> Closes: https://lore.kernel.org/oe-kbuild-all/202309201331.S2c1JL2h-lkp@xxxxxxxxx/ --- v1 -> v2: Moved the declaration of 'u32 nesting_level' inside #ifdef ACPI_APPLICATION ... #endif according to the unused variable warning of the kernel test robot. v1: Preliminary RFC version of the patch. drivers/acpi/acpica/utdebug.c | 40 ++++++++++++++++++++++++++++++----- 1 file changed, 35 insertions(+), 5 deletions(-) diff --git a/drivers/acpi/acpica/utdebug.c b/drivers/acpi/acpica/utdebug.c index c5f6c85a3a09..1faf7dc144f0 100644 --- a/drivers/acpi/acpica/utdebug.c +++ b/drivers/acpi/acpica/utdebug.c @@ -16,6 +16,8 @@ #define _COMPONENT ACPI_UTILITIES ACPI_MODULE_NAME("utdebug") +static DEFINE_SPINLOCK(acpi_utdebug_lock); + #ifdef ACPI_DEBUG_OUTPUT static acpi_thread_id acpi_gbl_previous_thread_id = (acpi_thread_id) 0xFFFFFFFF; static const char *acpi_gbl_function_entry_prefix = "----Entry"; @@ -60,13 +62,16 @@ void acpi_ut_init_stack_ptr_trace(void) void acpi_ut_track_stack_ptr(void) { acpi_size current_sp; + u32 nesting_level; if (¤t_sp < acpi_gbl_lowest_stack_pointer) { acpi_gbl_lowest_stack_pointer = ¤t_sp; } - if (acpi_gbl_nesting_level > acpi_gbl_deepest_nesting) { - acpi_gbl_deepest_nesting = acpi_gbl_nesting_level; + nesting_level = READ_ONCE(acpi_gbl_nesting_level); + + if (nesting_level > acpi_gbl_deepest_nesting) { + acpi_gbl_deepest_nesting = nesting_level; } } @@ -136,6 +141,7 @@ acpi_debug_print(u32 requested_debug_level, va_list args; #ifdef ACPI_APPLICATION int fill_count; + u32 nesting_level; #endif /* Check if debug output enabled */ @@ -156,7 +162,7 @@ acpi_debug_print(u32 requested_debug_level, } acpi_gbl_previous_thread_id = thread_id; - acpi_gbl_nesting_level = 0; + WRITE_ONCE(acpi_gbl_nesting_level, 0); } /* @@ -176,14 +182,16 @@ acpi_debug_print(u32 requested_debug_level, acpi_os_printf("[%u] ", (u32)thread_id); } - fill_count = 48 - acpi_gbl_nesting_level - + fill_count = 48 - READ_ONCE(acpi_gbl_nesting_level) - strlen(acpi_ut_trim_function_name(function_name)); if (fill_count < 0) { fill_count = 0; } + nesting_level = READ_ONCE(acpi_gbl_nesting_level); + acpi_os_printf("[%02d] %*s", - acpi_gbl_nesting_level, acpi_gbl_nesting_level + 1, " "); + nesting_level, nesting_level + 1, " "); acpi_os_printf("%s%*s: ", acpi_ut_trim_function_name(function_name), fill_count, " "); @@ -260,7 +268,10 @@ acpi_ut_trace(u32 line_number, const char *module_name, u32 component_id) { + spin_lock(&acpi_utdebug_lock); acpi_gbl_nesting_level++; + spin_unlock(&acpi_utdebug_lock); + acpi_ut_track_stack_ptr(); /* Check if enabled up-front for performance */ @@ -298,7 +309,10 @@ acpi_ut_trace_ptr(u32 line_number, u32 component_id, const void *pointer) { + spin_lock(&acpi_utdebug_lock); acpi_gbl_nesting_level++; + spin_unlock(&acpi_utdebug_lock); + acpi_ut_track_stack_ptr(); /* Check if enabled up-front for performance */ @@ -334,7 +348,10 @@ acpi_ut_trace_str(u32 line_number, const char *module_name, u32 component_id, const char *string) { + spin_lock(&acpi_utdebug_lock); acpi_gbl_nesting_level++; + spin_unlock(&acpi_utdebug_lock); + acpi_ut_track_stack_ptr(); /* Check if enabled up-front for performance */ @@ -370,7 +387,10 @@ acpi_ut_trace_u32(u32 line_number, const char *module_name, u32 component_id, u32 integer) { + spin_lock(&acpi_utdebug_lock); acpi_gbl_nesting_level++; + spin_unlock(&acpi_utdebug_lock); + acpi_ut_track_stack_ptr(); /* Check if enabled up-front for performance */ @@ -414,9 +434,11 @@ acpi_ut_exit(u32 line_number, acpi_gbl_function_exit_prefix); } + spin_lock(&acpi_utdebug_lock); if (acpi_gbl_nesting_level) { acpi_gbl_nesting_level--; } + spin_unlock(&acpi_utdebug_lock); } ACPI_EXPORT_SYMBOL(acpi_ut_exit) @@ -463,9 +485,11 @@ acpi_ut_status_exit(u32 line_number, } } + spin_lock(&acpi_utdebug_lock); if (acpi_gbl_nesting_level) { acpi_gbl_nesting_level--; } + spin_unlock(&acpi_utdebug_lock); } ACPI_EXPORT_SYMBOL(acpi_ut_status_exit) @@ -502,9 +526,11 @@ acpi_ut_value_exit(u32 line_number, ACPI_FORMAT_UINT64(value)); } + spin_lock(&acpi_utdebug_lock); if (acpi_gbl_nesting_level) { acpi_gbl_nesting_level--; } + spin_unlock(&acpi_utdebug_lock); } ACPI_EXPORT_SYMBOL(acpi_ut_value_exit) @@ -540,9 +566,11 @@ acpi_ut_ptr_exit(u32 line_number, acpi_gbl_function_exit_prefix, ptr); } + spin_lock(&acpi_utdebug_lock); if (acpi_gbl_nesting_level) { acpi_gbl_nesting_level--; } + spin_unlock(&acpi_utdebug_lock); } /******************************************************************************* @@ -577,9 +605,11 @@ acpi_ut_str_exit(u32 line_number, acpi_gbl_function_exit_prefix, string); } + spin_lock(&acpi_utdebug_lock); if (acpi_gbl_nesting_level) { acpi_gbl_nesting_level--; } + spin_unlock(&acpi_utdebug_lock); } /******************************************************************************* -- 2.34.1
