xen: x86: irq: initialize irq desc in create_irq()

While building xen with GCC 14.2.1 with "-fcondition-coverage" option
or with "-Og", the compiler produces a false positive warning:

  arch/x86/irq.c: In function ‘create_irq’:
  arch/x86/irq.c:281:11: error: ‘desc’ may be used uninitialized [-Werror=maybe-uninitialized]
    281 |     ret = init_one_irq_desc(desc);
        |           ^~~~~~~~~~~~~~~~~~~~~~~
  arch/x86/irq.c:269:22: note: ‘desc’ was declared here
    269 |     struct irq_desc *desc;
        |                      ^~~~
  cc1: all warnings being treated as errors
  make[2]: *** [Rules.mk:252: arch/x86/irq.o] Error 1

While we have signed/unsigned comparison both in "for" loop and in
"if" statement, this still can't lead to use of uninitialized "desc",
as either loop will be executed at least once, or the function will
return early. So this is a clearly false positive warning due to a
bug [1] in GCC.

Initialize "desc" with NULL to make GCC happy.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119665

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index dd8d921f18f6422dbdde3c32c364506a3b7d6bc4..38ac0823d723db923ebf63114664245025d0fc27 100644 (file)
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -265,7 +265,7 @@ void __init clear_irq_vector(int irq)
 int create_irq(nodeid_t node, bool grant_access)
 {
     int irq, ret;
-    struct irq_desc *desc;
+    struct irq_desc *desc = NULL ; /* gcc14 -Og or -fcondition-coverage */
 
     for (irq = nr_irqs_gsi; irq < nr_irqs; irq++)
     {