drivers/hv/channel_mgmt.c:785:22: warning: Assigned value is garbage or undefined [clang-analyzer-core.uninitialized.Assign]

From: kernel test robot
Date: Sun Jul 25 2021 - 23:43:26 EST



Hi Haiyang,

First bad commit (maybe != root cause):

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: d8079fac168168b25677dc16c00ffaf9fb7df723
commit: 7c9ff3deeee61b253715dcf968a6307af148c9b2 Drivers: hv: vmbus: Fix duplicate CPU assignments within a device
date: 6 days ago
:::::: branch date: 11 hours ago
:::::: commit date: 6 days ago
config: x86_64-randconfig-c001-20210725 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 3f2c1e99e44d028d5e9dd685f3c568f2661f2f68)
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 x86_64 cross compiling tool for clang build
# apt-get install binutils-x86-64-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c9ff3deeee61b253715dcf968a6307af148c9b2
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout 7c9ff3deeee61b253715dcf968a6307af148c9b2
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross clang-analyzer ARCH=x86_64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>


clang-analyzer warnings: (new ones prefixed by >>)
^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hid/hid-core.c:1601:3: note: Taking false branch
if (field->logical_minimum < 0) /* signed values */
^
drivers/hid/hid-core.c:1605:44: note: Passing value via 4th parameter 'n'
implement(hid, data, offset + n * size, size,
^~~~
drivers/hid/hid-core.c:1605:4: note: Calling 'implement'
implement(hid, data, offset + n * size, size,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hid/hid-core.c:1421:15: note: Assuming 'n' is <= 32
if (unlikely(n > 32)) {
^
include/linux/compiler.h:78:42: note: expanded from macro 'unlikely'
# define unlikely(x) __builtin_expect(!!(x), 0)
^
drivers/hid/hid-core.c:1421:2: note: Taking false branch
if (unlikely(n > 32)) {
^
drivers/hid/hid-core.c:1425:13: note: Assuming 'n' is >= 32
} else if (n < 32) {
^~~~~~
drivers/hid/hid-core.c:1425:9: note: Taking false branch
} else if (n < 32) {
^
drivers/hid/hid-core.c:1437:30: note: Passing the value 32 via 3rd parameter 'n'
__implement(report, offset, n, value);
^
drivers/hid/hid-core.c:1437:2: note: Calling '__implement'
__implement(report, offset, n, value);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hid/hid-core.c:1400:9: note: Assuming the condition is false
while (n - bits_to_set >= 0) {
^~~~~~~~~~~~~~~~~~~~
drivers/hid/hid-core.c:1400:2: note: Loop condition is false. Execution continues on line 1411
while (n - bits_to_set >= 0) {
^
drivers/hid/hid-core.c:1411:6: note: 'n' is 32
if (n) {
^
drivers/hid/hid-core.c:1411:2: note: Taking true branch
if (n) {
^
drivers/hid/hid-core.c:1412:22: note: The result of the left shift is undefined due to shifting by '32', which is greater or equal to the width of type 'unsigned int'
u8 bit_mask = ((1U << n) - 1);
^ ~
drivers/hid/hid-core.c:1984:3: warning: Value stored to 'len' is never read [clang-analyzer-deadcode.DeadStores]
len += sprintf(buf + len, "%shidraw%d", len ? "," : "",
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hid/hid-core.c:1984:3: note: Value stored to 'len' is never read
len += sprintf(buf + len, "%shidraw%d", len ? "," : "",
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suppressed 5 warnings (5 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.
6 warnings generated.
Suppressed 6 warnings (6 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.
6 warnings generated.
Suppressed 6 warnings (6 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.
7 warnings generated.
Suppressed 7 warnings (7 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.
4 warnings generated.
Suppressed 4 warnings (4 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.
4 warnings generated.
Suppressed 4 warnings (4 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.
4 warnings generated.
Suppressed 4 warnings (4 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.
4 warnings generated.
Suppressed 4 warnings (4 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.
4 warnings generated.
Suppressed 4 warnings (4 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.
4 warnings generated.
Suppressed 4 warnings (4 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.
4 warnings generated.
Suppressed 4 warnings (4 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.
5 warnings generated.
Suppressed 5 warnings (5 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.
4 warnings generated.
Suppressed 4 warnings (4 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 (3 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.
9 warnings generated.
Suppressed 9 warnings (8 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.
5 warnings generated.
Suppressed 5 warnings (5 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.
6 warnings generated.
drivers/hv/channel_mgmt.c:785:22: warning: Assigned value is garbage or undefined [clang-analyzer-core.uninitialized.Assign]
channel->target_cpu = target_cpu;
^
drivers/hv/channel_mgmt.c:608:2: note: Left side of '&&' is false
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
^
include/linux/list.h:628:13: note: expanded from macro 'list_for_each_entry'
for (pos = list_first_entry(head, typeof(*pos), member); \
^
include/linux/list.h:522:2: note: expanded from macro 'list_first_entry'
list_entry((ptr)->next, type, member)
^
include/linux/list.h:511:2: note: expanded from macro 'list_entry'
container_of(ptr, type, member)
^
include/linux/kernel.h:495:61: note: expanded from macro 'container_of'
BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \
^
drivers/hv/channel_mgmt.c:608:2: note: Taking false branch
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
^
include/linux/list.h:628:13: note: expanded from macro 'list_for_each_entry'
for (pos = list_first_entry(head, typeof(*pos), member); \
^
include/linux/list.h:522:2: note: expanded from macro 'list_first_entry'
list_entry((ptr)->next, type, member)
^
include/linux/list.h:511:2: note: expanded from macro 'list_entry'
container_of(ptr, type, member)
^
note: (skipping 2 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
include/linux/compiler_types.h:328:2: note: expanded from macro 'compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
^
include/linux/compiler_types.h:316:2: note: expanded from macro '_compiletime_assert'
__compiletime_assert(condition, msg, prefix, suffix)
^
include/linux/compiler_types.h:308:3: note: expanded from macro '__compiletime_assert'
if (!(condition)) \
^
drivers/hv/channel_mgmt.c:608:2: note: Loop condition is false. Exiting loop
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
^
include/linux/list.h:628:13: note: expanded from macro 'list_for_each_entry'
for (pos = list_first_entry(head, typeof(*pos), member); \
^
include/linux/list.h:522:2: note: expanded from macro 'list_first_entry'
list_entry((ptr)->next, type, member)
^
include/linux/list.h:511:2: note: expanded from macro 'list_entry'
container_of(ptr, type, member)
^
note: (skipping 2 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
include/linux/compiler_types.h:328:2: note: expanded from macro 'compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
^
include/linux/compiler_types.h:316:2: note: expanded from macro '_compiletime_assert'
__compiletime_assert(condition, msg, prefix, suffix)
^
include/linux/compiler_types.h:306:2: note: expanded from macro '__compiletime_assert'
do { \
^
drivers/hv/channel_mgmt.c:608:2: note: Loop condition is false. Execution continues on line 619
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
^
include/linux/list.h:628:2: note: expanded from macro 'list_for_each_entry'
for (pos = list_first_entry(head, typeof(*pos), member); \
^
drivers/hv/channel_mgmt.c:619:2: note: Calling 'init_vp_index'
init_vp_index(newchannel);
^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hv/channel_mgmt.c:732:2: note: 'target_cpu' declared without an initial value
u32 target_cpu;
^~~~~~~~~~~~~~
drivers/hv/channel_mgmt.c:735:7: note: Assuming the condition is false
if ((vmbus_proto_version == VERSION_WS2008) ||
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hv/channel_mgmt.c:735:6: note: Left side of '||' is false
if ((vmbus_proto_version == VERSION_WS2008) ||
^
drivers/hv/channel_mgmt.c:736:7: note: Assuming the condition is false
(vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hv/channel_mgmt.c:735:6: note: Left side of '||' is false
if ((vmbus_proto_version == VERSION_WS2008) ||
^
drivers/hv/channel_mgmt.c:736:48: note: Assuming 'perf_chn' is true
(vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
^~~~~~~~~
drivers/hv/channel_mgmt.c:735:6: note: Left side of '||' is false
if ((vmbus_proto_version == VERSION_WS2008) ||
^
drivers/hv/channel_mgmt.c:737:7: note: Calling 'alloc_cpumask_var'
!alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/cpumask.h:740:2: note: Returning the value 1, which participates in a condition later
return true;
^~~~~~~~~~~
drivers/hv/channel_mgmt.c:737:7: note: Returning from 'alloc_cpumask_var'
!alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +785 drivers/hv/channel_mgmt.c

a119845f6e98c8 K. Y. Srinivasan 2012-12-01 714 a119845f6e98c8 K. Y. Srinivasan 2012-12-01 715 /*
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 716 * Starting with Win8, we can statically distribute the incoming
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 717 * channel interrupt load by binding a channel to VCPU.
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 718 *
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 719 * For pre-win8 hosts or non-performance critical channels we assign the
d570aec0f2154e Andrea Parri (Microsoft 2020-04-06 720) * VMBUS_CONNECT_CPU.
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 721) *
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 722) * Starting with win8, performance critical channels will be distributed
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 723) * evenly among all the available NUMA nodes. Once the node is assigned,
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 724) * we will assign the CPU based on a simple round robin scheme.
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 725 */
afaa33da08abd1 Andrea Parri (Microsoft 2020-05-22 726) static void init_vp_index(struct vmbus_channel *channel)
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 727 {
afaa33da08abd1 Andrea Parri (Microsoft 2020-05-22 728) bool perf_chn = hv_is_perf_channel(channel);
7c9ff3deeee61b Haiyang Zhang 2021-07-16 729 u32 i, ncpu = num_online_cpus();
25355252607ca2 Dexuan Cui 2018-09-23 730 cpumask_var_t available_mask;
9f01ec53458d9e K. Y. Srinivasan 2015-08-05 731 struct cpumask *alloced_mask;
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 732) u32 target_cpu;
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 733) int numa_node;
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 734 a119845f6e98c8 K. Y. Srinivasan 2012-12-01 735 if ((vmbus_proto_version == VERSION_WS2008) ||
25355252607ca2 Dexuan Cui 2018-09-23 736 (vmbus_proto_version == VERSION_WIN7) || (!perf_chn) ||
25355252607ca2 Dexuan Cui 2018-09-23 737 !alloc_cpumask_var(&available_mask, GFP_KERNEL)) {
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 738 /*
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 739 * Prior to win8, all channel interrupts are
d570aec0f2154e Andrea Parri (Microsoft 2020-04-06 740) * delivered on VMBUS_CONNECT_CPU.
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 741 * Also if the channel is not a performance critical
d570aec0f2154e Andrea Parri (Microsoft 2020-04-06 742) * channel, bind it to VMBUS_CONNECT_CPU.
d570aec0f2154e Andrea Parri (Microsoft 2020-04-06 743) * In case alloc_cpumask_var() fails, bind it to
d570aec0f2154e Andrea Parri (Microsoft 2020-04-06 744) * VMBUS_CONNECT_CPU.
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 745 */
d570aec0f2154e Andrea Parri (Microsoft 2020-04-06 746) channel->target_cpu = VMBUS_CONNECT_CPU;
afaa33da08abd1 Andrea Parri (Microsoft 2020-05-22 747) if (perf_chn)
afaa33da08abd1 Andrea Parri (Microsoft 2020-05-22 748) hv_set_alloced_cpu(VMBUS_CONNECT_CPU);
d3ba720dd58cdf K. Y. Srinivasan 2014-04-08 749 return;
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 750 }
ce59fec836a9b4 Vitaly Kuznetsov 2015-05-06 751 7c9ff3deeee61b Haiyang Zhang 2021-07-16 752 for (i = 1; i <= ncpu + 1; i++) {
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 753 while (true) {
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 754) numa_node = next_numa_node_id++;
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 755) if (numa_node == nr_node_ids) {
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 756) next_numa_node_id = 0;
509879bdb30b8e K. Y. Srinivasan 2016-09-02 757 continue;
509879bdb30b8e K. Y. Srinivasan 2016-09-02 758 }
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 759) if (cpumask_empty(cpumask_of_node(numa_node)))
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 760 continue;
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 761 break;
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 762 }
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 763) alloced_mask = &hv_context.hv_numa_map[numa_node];
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 764 9f01ec53458d9e K. Y. Srinivasan 2015-08-05 765 if (cpumask_weight(alloced_mask) ==
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 766) cpumask_weight(cpumask_of_node(numa_node))) {
ce59fec836a9b4 Vitaly Kuznetsov 2015-05-06 767 /*
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 768 * We have cycled through all the CPUs in the node;
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 769 * reset the alloced map.
ce59fec836a9b4 Vitaly Kuznetsov 2015-05-06 770 */
9f01ec53458d9e K. Y. Srinivasan 2015-08-05 771 cpumask_clear(alloced_mask);
ce59fec836a9b4 Vitaly Kuznetsov 2015-05-06 772 }
ce59fec836a9b4 Vitaly Kuznetsov 2015-05-06 773 7c9ff3deeee61b Haiyang Zhang 2021-07-16 774 cpumask_xor(available_mask, alloced_mask,
7c9ff3deeee61b Haiyang Zhang 2021-07-16 775 cpumask_of_node(numa_node));
79fd8e706637a5 Vitaly Kuznetsov 2016-01-27 776 8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 777) target_cpu = cpumask_first(available_mask);
8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 778) cpumask_set_cpu(target_cpu, alloced_mask);
1f656ff3fdddc2 K. Y. Srinivasan 2015-05-30 779 7c9ff3deeee61b Haiyang Zhang 2021-07-16 780 if (channel->offermsg.offer.sub_channel_index >= ncpu ||
7c9ff3deeee61b Haiyang Zhang 2021-07-16 781 i > ncpu || !hv_cpuself_used(target_cpu, channel))
7c9ff3deeee61b Haiyang Zhang 2021-07-16 782 break;
7c9ff3deeee61b Haiyang Zhang 2021-07-16 783 }
7c9ff3deeee61b Haiyang Zhang 2021-07-16 784 8ef4c4abbbcdcd Andrea Parri (Microsoft 2020-04-06 @785) channel->target_cpu = target_cpu;
25355252607ca2 Dexuan Cui 2018-09-23 786 25355252607ca2 Dexuan Cui 2018-09-23 787 free_cpumask_var(available_mask);
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 788 }
a119845f6e98c8 K. Y. Srinivasan 2012-12-01 789
:::::: The code at line 785 was first introduced by commit
:::::: 8ef4c4abbbcdcd9d4bc0fd9454df03e6dac24b73 Drivers: hv: vmbus: Remove the unused HV_LOCALIZED channel affinity logic

:::::: TO: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
:::::: CC: Wei Liu <wei.liu@xxxxxxxxxx>

---
0-DAY CI Kernel Test Service, Intel Corporation
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