From: Siddh Raman Pant code@siddh.me
[ Upstream commit 625395c4a0f4775e0fe00f616888d2e6c1ba49db ]
GCC-12 started triggering a new warning:
arch/x86/mm/numa.c: In function ‘cpumask_of_node’: arch/x86/mm/numa.c:916:39: warning: the comparison will always evaluate as ‘false’ for the address of ‘node_to_cpumask_map’ will never be NULL [-Waddress] 916 | if (node_to_cpumask_map[node] == NULL) { | ^~
node_to_cpumask_map is of type cpumask_var_t[].
When CONFIG_CPUMASK_OFFSTACK is set, cpumask_var_t is typedef'd to a pointer for dynamic allocation, else to an array of one element. The "wicked game" can be checked on line 700 of include/linux/cpumask.h.
The original code in debug_cpumask_set_cpu() and cpumask_of_node() were probably written by the original authors with CONFIG_CPUMASK_OFFSTACK=y (i.e. dynamic allocation) in mind, checking if the cpumask was available via a direct NULL check.
When CONFIG_CPUMASK_OFFSTACK is not set, GCC gives the above warning while compiling the kernel.
Fix that by using cpumask_available(), which does the NULL check when CONFIG_CPUMASK_OFFSTACK is set, otherwise returns true. Use it wherever such checks are made.
Conditional definitions of cpumask_available() can be found along with the definition of cpumask_var_t. Check the cpumask.h reference mentioned above.
Fixes: c032ef60d1aa ("cpumask: convert node_to_cpumask_map[] to cpumask_var_t") Fixes: de2d9445f162 ("x86: Unify node_to_cpumask_map handling between 32 and 64bit") Signed-off-by: Siddh Raman Pant code@siddh.me Signed-off-by: Ingo Molnar mingo@kernel.org Link: https://lore.kernel.org/r/20220731160913.632092-1-code@siddh.me Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/mm/numa.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c index e94da744386f..9dc31996c7ed 100644 --- a/arch/x86/mm/numa.c +++ b/arch/x86/mm/numa.c @@ -861,7 +861,7 @@ void debug_cpumask_set_cpu(int cpu, int node, bool enable) return; } mask = node_to_cpumask_map[node]; - if (!mask) { + if (!cpumask_available(mask)) { pr_err("node_to_cpumask_map[%i] NULL\n", node); dump_stack(); return; @@ -907,7 +907,7 @@ const struct cpumask *cpumask_of_node(int node) dump_stack(); return cpu_none_mask; } - if (node_to_cpumask_map[node] == NULL) { + if (!cpumask_available(node_to_cpumask_map[node])) { printk(KERN_WARNING "cpumask_of_node(%d): no node_to_cpumask_map!\n", node);