From: Siddh Raman Pant <code@xxxxxxxx>
[ 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@xxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220731160913.632092-1-code@xxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 25504d5aa816..15661129794c 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -826,7 +826,7 @@ 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;
@@ -872,7 +872,7 @@ 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);
--
2.35.1
