diff mbox series

[v1,1/1] acpica: use spinlocks to fix the data-races reported by the KCSAN

Message ID 20230920000139.15533-1-mirsad.todorovac@alu.unizg.hr
State New
Headers show
Series [v1,1/1] acpica: use spinlocks to fix the data-races reported by the KCSAN | expand

Commit Message

Mirsad Todorovac Sept. 20, 2023, 12:01 a.m. UTC 
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@alu.unizg.hr>
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@FreeBSD.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Erik Kaneda <erik.kaneda@intel.com>
Cc: Bob Moore <robert.moore@intel.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-acpi@vger.kernel.org
Cc: acpica-devel@lists.linuxfoundation.org
Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
---
v1:
 Preliminary RFC version of the patch.

 drivers/acpi/acpica/utdebug.c | 40 ++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

Comments

kernel test robot Sept. 20, 2023, 5:37 a.m. UTC | #1 
Hi Mirsad,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.6-rc2 next-20230920]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Mirsad-Goran-Todorovac/acpica-use-spinlocks-to-fix-the-data-races-reported-by-the-KCSAN/20230920-080345
base:   linus/master
patch link:    https://lore.kernel.org/r/20230920000139.15533-1-mirsad.todorovac%40alu.unizg.hr
patch subject: [PATCH v1 1/1] acpica: use spinlocks to fix the data-races reported by the KCSAN
config: i386-randconfig-012-20230920 (https://download.01.org/0day-ci/archive/20230920/202309201308.5ZBJFbjh-lkp@intel.com/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230920/202309201308.5ZBJFbjh-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309201308.5ZBJFbjh-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/spinlock.h:89,
                    from include/linux/wait.h:9,
                    from include/linux/pid.h:6,
                    from include/linux/sched.h:14,
                    from include/acpi/platform/aclinux.h:55,
                    from include/acpi/platform/acenv.h:160,
                    from include/acpi/acpi.h:22,
                    from drivers/acpi/acpica/utdebug.c:12:
>> drivers/acpi/acpica/utdebug.c:19:24: warning: 'acpi_utdebug_lock' defined but not used [-Wunused-variable]
      19 | static DEFINE_SPINLOCK(acpi_utdebug_lock);
         |                        ^~~~~~~~~~~~~~~~~
   include/linux/spinlock_types.h:43:39: note: in definition of macro 'DEFINE_SPINLOCK'
      43 | #define DEFINE_SPINLOCK(x) spinlock_t x = __SPIN_LOCK_UNLOCKED(x)
         |                                       ^


vim +/acpi_utdebug_lock +19 drivers/acpi/acpica/utdebug.c

    11	
  > 12	#include <acpi/acpi.h>
    13	#include "accommon.h"
    14	#include "acinterp.h"
    15	
    16	#define _COMPONENT          ACPI_UTILITIES
    17	ACPI_MODULE_NAME("utdebug")
    18	
  > 19	static DEFINE_SPINLOCK(acpi_utdebug_lock);
    20
diff mbox series

Patch

diff --git a/drivers/acpi/acpica/utdebug.c b/drivers/acpi/acpica/utdebug.c
index c5f6c85a3a09..148f2b820c88 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 (&current_sp < acpi_gbl_lowest_stack_pointer) {
 		acpi_gbl_lowest_stack_pointer = &current_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;
 	}
 }
 
@@ -137,6 +142,7 @@  acpi_debug_print(u32 requested_debug_level,
 #ifdef ACPI_APPLICATION
 	int fill_count;
 #endif
+	u32 nesting_level;
 
 	/* 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);
 }
 
 /*******************************************************************************