CC: [email protected]
BCC: [email protected]
TO: Maarten Lankhorst <[email protected]>
CC: Junxiao Chang <[email protected]>

tree:   https://github.com/intel/linux-intel-lts.git 5.15/linux
head:   28355ba25d3468058a5470273bc7b9c8b411b958
commit: 53956aadc1f3755f43e9a8d6741cb2b1d4c58ac6 [336/2399] kernel/locking: Add 
context to ww_mutex_trylock()
:::::: branch date: 6 days ago
:::::: commit date: 5 weeks ago
config: arm-randconfig-c002-20220327 
(https://download.01.org/0day-ci/archive/20220327/[email protected]/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 
0f6d9501cf49ce02937099350d08f20c4af86f3d)
reproduce (this is a W=1 build):
        wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # 
https://github.com/intel/linux-intel-lts/commit/53956aadc1f3755f43e9a8d6741cb2b1d4c58ac6
        git remote add intel-lts https://github.com/intel/linux-intel-lts.git
        git fetch --no-tags intel-lts 5.15/linux
        git checkout 53956aadc1f3755f43e9a8d6741cb2b1d4c58ac6
        # save the config file to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm 
clang-analyzer 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>


clang-analyzer warnings: (new ones prefixed by >>)
   arch/arm/kernel/devtree.c:227:2: note: Value assigned to 'mdesc'
           mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/arm/kernel/devtree.c:229:6: note: Assuming 'mdesc' is null
           if (!mdesc) {
               ^~~~~~
   arch/arm/kernel/devtree.c:229:2: note: Taking true branch
           if (!mdesc) {
           ^
   arch/arm/kernel/devtree.c:239:10: note: Assuming 'size' is <= 0
                   while (size > 0) {
                          ^~~~~~~~
   arch/arm/kernel/devtree.c:239:3: note: Loop condition is false. Execution 
continues on line 244
                   while (size > 0) {
                   ^
   arch/arm/kernel/devtree.c:250:6: note: Access to field 'dt_fixup' results in 
a dereference of a null pointer (loaded from variable 'mdesc')
           if (mdesc->dt_fixup)
               ^~~~~
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   3 warnings generated.
   Suppressed 3 warnings (1 in non-user code, 2 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   2 warnings generated.
   Suppressed 2 warnings (1 in non-user code, 1 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   2 warnings generated.
   drivers/phy/motorola/phy-mapphone-mdm6600.c:424:3: warning: Value stored to 
'error' is never read [clang-analyzer-deadcode.DeadStores]
                   error = -ETIMEDOUT;
                   ^       ~~~~~~~~~~
   drivers/phy/motorola/phy-mapphone-mdm6600.c:424:3: note: Value stored to 
'error' is never read
                   error = -ETIMEDOUT;
                   ^       ~~~~~~~~~~
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   2 warnings generated.
   drivers/phy/qualcomm/phy-qcom-qusb2.c:562:17: warning: Value stored to 'dev' 
during its initialization is never read [clang-analyzer-deadcode.DeadStores]
           struct device *dev = &qphy->phy->dev;
                          ^~~   ~~~~~~~~~~~~~~~
   drivers/phy/qualcomm/phy-qcom-qusb2.c:562:17: note: Value stored to 'dev' 
during its initialization is never read
           struct device *dev = &qphy->phy->dev;
                          ^~~   ~~~~~~~~~~~~~~~
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   2 warnings generated.
   drivers/phy/ralink/phy-mt7621-pci.c:120:17: warning: Value stored to 'dev' 
during its initialization is never read [clang-analyzer-deadcode.DeadStores]
           struct device *dev = phy->dev;
                          ^~~   ~~~~~~~~
   drivers/phy/ralink/phy-mt7621-pci.c:120:17: note: Value stored to 'dev' 
during its initialization is never read
           struct device *dev = phy->dev;
                          ^~~   ~~~~~~~~
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   3 warnings generated.
>> kernel/locking/test-ww_mutex.c:172:2: warning: Undefined or garbage value 
>> returned to caller [clang-analyzer-core.uninitialized.UndefReturn]
           return ret;
           ^
   kernel/locking/test-ww_mutex.c:625:2: note: Loop condition is false.  
Exiting loop
           printk(KERN_INFO "Beginning ww mutex selftests\n");
           ^
   include/linux/printk.h:450:26: note: expanded from macro 'printk'
   #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
                            ^
   include/linux/printk.h:421:3: note: expanded from macro 'printk_index_wrap'
                   __printk_index_emit(_fmt, NULL, NULL);                  \
                   ^
   include/linux/printk.h:396:34: note: expanded from macro 
'__printk_index_emit'
   #define __printk_index_emit(...) do {} while (0)
                                    ^
   kernel/locking/test-ww_mutex.c:628:6: note: Assuming 'wq' is non-null
           if (!wq)
               ^~~
   kernel/locking/test-ww_mutex.c:628:2: note: Taking false branch
           if (!wq)
           ^
   kernel/locking/test-ww_mutex.c:632:6: note: Assuming 'ret' is 0
           if (ret)
               ^~~
   kernel/locking/test-ww_mutex.c:632:2: note: Taking false branch
           if (ret)
           ^
   kernel/locking/test-ww_mutex.c:636:6: note: 'ret' is 0
           if (ret)
               ^~~
   kernel/locking/test-ww_mutex.c:636:2: note: Taking false branch
           if (ret)
           ^
   kernel/locking/test-ww_mutex.c:639:8: note: Calling 'test_aa'
           ret = test_aa(true);
                 ^~~~~~~~~~~~~
   kernel/locking/test-ww_mutex.c:125:2: note: 'ret' declared without an 
initial value
           int ret;
           ^~~~~~~
   kernel/locking/test-ww_mutex.c:126:21: note: 'trylock' is true
           const char *from = trylock ? "trylock" : "lock";
                              ^~~~~~~
   kernel/locking/test-ww_mutex.c:126:21: note: '?' condition is true
   kernel/locking/test-ww_mutex.c:131:7: note: 'trylock' is true
           if (!trylock) {
                ^~~~~~~
   kernel/locking/test-ww_mutex.c:131:2: note: Taking false branch
           if (!trylock) {
           ^
   kernel/locking/test-ww_mutex.c:138:7: note: Assuming the condition is true
                   if (!ww_mutex_trylock(&mutex, &ctx)) {
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/locking/test-ww_mutex.c:138:3: note: Taking true branch
                   if (!ww_mutex_trylock(&mutex, &ctx)) {
                   ^
   kernel/locking/test-ww_mutex.c:139:4: note: Loop condition is false.  
Exiting loop
                           pr_err("%s: initial trylock failed!\n", __func__);
                           ^
   include/linux/printk.h:493:2: note: expanded from macro 'pr_err'
           printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
           ^
   include/linux/printk.h:450:26: note: expanded from macro 'printk'
   #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
                            ^
   include/linux/printk.h:421:3: note: expanded from macro 'printk_index_wrap'
                   __printk_index_emit(_fmt, NULL, NULL);                  \
                   ^
   include/linux/printk.h:396:34: note: expanded from macro 
'__printk_index_emit'
   #define __printk_index_emit(...) do {} while (0)
                                    ^
   kernel/locking/test-ww_mutex.c:140:4: note: Control jumps to line 171
                           goto out;
                           ^
   kernel/locking/test-ww_mutex.c:172:2: note: Undefined or garbage value 
returned to caller
           return ret;
           ^      ~~~
   Suppressed 2 warnings (1 in non-user code, 1 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   1 warning generated.
   Suppressed 1 warnings (1 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use 
-system-headers to display errors from system headers as well.
   2 warnings generated.
   lib/mpi/mpi-pow.c:164:10: warning: The result of the left shift is undefined 
due to shifting by '32', which is greater or equal to the width of type 
'mpi_limb_t' [clang-analyzer-core.UndefinedBinaryOperatorResult]
                   e = (e << c) << 1;      /* shift the exp bits to the left, 
lose msb */
                          ^  ~
   lib/mpi/mpi-pow.c:49:6: note: Assuming 'msize' is not equal to 0
           if (!msize)
               ^~~~~~
   lib/mpi/mpi-pow.c:49:2: note: Taking false branch
           if (!msize)
           ^
   lib/mpi/mpi-pow.c:52:6: note: Assuming 'esize' is not equal to 0
           if (!esize) {
               ^~~~~~
   lib/mpi/mpi-pow.c:52:2: note: Taking false branch
           if (!esize) {
           ^
   lib/mpi/mpi-pow.c:71:6: note: Assuming 'mp' is non-null
           if (!mp)
               ^~~
   lib/mpi/mpi-pow.c:71:2: note: Taking false branch

vim +172 kernel/locking/test-ww_mutex.c

f2a5fec17395f2 Chris Wilson      2016-12-01  120  
53956aadc1f375 Maarten Lankhorst 2021-09-09  121  static int test_aa(bool 
trylock)
c22fb3807fd0a3 Chris Wilson      2016-12-01  122  {
c22fb3807fd0a3 Chris Wilson      2016-12-01  123        struct ww_mutex mutex;
c22fb3807fd0a3 Chris Wilson      2016-12-01  124        struct ww_acquire_ctx 
ctx;
c22fb3807fd0a3 Chris Wilson      2016-12-01  125        int ret;
53956aadc1f375 Maarten Lankhorst 2021-09-09  126        const char *from = 
trylock ? "trylock" : "lock";
c22fb3807fd0a3 Chris Wilson      2016-12-01  127  
c22fb3807fd0a3 Chris Wilson      2016-12-01  128        ww_mutex_init(&mutex, 
&ww_class);
c22fb3807fd0a3 Chris Wilson      2016-12-01  129        ww_acquire_init(&ctx, 
&ww_class);
c22fb3807fd0a3 Chris Wilson      2016-12-01  130  
53956aadc1f375 Maarten Lankhorst 2021-09-09  131        if (!trylock) {
53956aadc1f375 Maarten Lankhorst 2021-09-09  132                ret = 
ww_mutex_lock(&mutex, &ctx);
53956aadc1f375 Maarten Lankhorst 2021-09-09  133                if (ret) {
53956aadc1f375 Maarten Lankhorst 2021-09-09  134                        
pr_err("%s: initial lock failed!\n", __func__);
53956aadc1f375 Maarten Lankhorst 2021-09-09  135                        goto 
out;
53956aadc1f375 Maarten Lankhorst 2021-09-09  136                }
53956aadc1f375 Maarten Lankhorst 2021-09-09  137        } else {
53956aadc1f375 Maarten Lankhorst 2021-09-09  138                if 
(!ww_mutex_trylock(&mutex, &ctx)) {
53956aadc1f375 Maarten Lankhorst 2021-09-09  139                        
pr_err("%s: initial trylock failed!\n", __func__);
53956aadc1f375 Maarten Lankhorst 2021-09-09  140                        goto 
out;
53956aadc1f375 Maarten Lankhorst 2021-09-09  141                }
53956aadc1f375 Maarten Lankhorst 2021-09-09  142        }
53956aadc1f375 Maarten Lankhorst 2021-09-09  143  
53956aadc1f375 Maarten Lankhorst 2021-09-09  144        if 
(ww_mutex_trylock(&mutex, NULL))  {
53956aadc1f375 Maarten Lankhorst 2021-09-09  145                pr_err("%s: 
trylocked itself without context from %s!\n", __func__, from);
53956aadc1f375 Maarten Lankhorst 2021-09-09  146                
ww_mutex_unlock(&mutex);
53956aadc1f375 Maarten Lankhorst 2021-09-09  147                ret = -EINVAL;
53956aadc1f375 Maarten Lankhorst 2021-09-09  148                goto out;
53956aadc1f375 Maarten Lankhorst 2021-09-09  149        }
c22fb3807fd0a3 Chris Wilson      2016-12-01  150  
53956aadc1f375 Maarten Lankhorst 2021-09-09  151        if 
(ww_mutex_trylock(&mutex, &ctx))  {
53956aadc1f375 Maarten Lankhorst 2021-09-09  152                pr_err("%s: 
trylocked itself with context from %s!\n", __func__, from);
c22fb3807fd0a3 Chris Wilson      2016-12-01  153                
ww_mutex_unlock(&mutex);
c22fb3807fd0a3 Chris Wilson      2016-12-01  154                ret = -EINVAL;
c22fb3807fd0a3 Chris Wilson      2016-12-01  155                goto out;
c22fb3807fd0a3 Chris Wilson      2016-12-01  156        }
c22fb3807fd0a3 Chris Wilson      2016-12-01  157  
c22fb3807fd0a3 Chris Wilson      2016-12-01  158        ret = 
ww_mutex_lock(&mutex, &ctx);
c22fb3807fd0a3 Chris Wilson      2016-12-01  159        if (ret != -EALREADY) {
53956aadc1f375 Maarten Lankhorst 2021-09-09  160                pr_err("%s: 
missed deadlock for recursing, ret=%d from %s\n",
53956aadc1f375 Maarten Lankhorst 2021-09-09  161                       
__func__, ret, from);
c22fb3807fd0a3 Chris Wilson      2016-12-01  162                if (!ret)
c22fb3807fd0a3 Chris Wilson      2016-12-01  163                        
ww_mutex_unlock(&mutex);
c22fb3807fd0a3 Chris Wilson      2016-12-01  164                ret = -EINVAL;
c22fb3807fd0a3 Chris Wilson      2016-12-01  165                goto out;
c22fb3807fd0a3 Chris Wilson      2016-12-01  166        }
c22fb3807fd0a3 Chris Wilson      2016-12-01  167  
53956aadc1f375 Maarten Lankhorst 2021-09-09  168        ww_mutex_unlock(&mutex);
c22fb3807fd0a3 Chris Wilson      2016-12-01  169        ret = 0;
c22fb3807fd0a3 Chris Wilson      2016-12-01  170  out:
c22fb3807fd0a3 Chris Wilson      2016-12-01  171        ww_acquire_fini(&ctx);
c22fb3807fd0a3 Chris Wilson      2016-12-01 @172        return ret;
c22fb3807fd0a3 Chris Wilson      2016-12-01  173  }
c22fb3807fd0a3 Chris Wilson      2016-12-01  174  

:::::: The code at line 172 was first introduced by commit
:::::: c22fb3807fd0a3bdd98c13c4d2190ab064e6c09d locking/ww_mutex: Add 
kselftests for ww_mutex AA deadlock detection

:::::: TO: Chris Wilson <[email protected]>
:::::: CC: Ingo Molnar <[email protected]>

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp
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