Fix compile failure related to aliasing (gcc 4.4.5)

My version of gcc would complain about "dereferencing pointer does
break strict-aliasing rules" because of a (harmless) pointer cast.

This patch adds a helper void pointer to make the assignment explicit,
which avoids the cast and hence silences the warning.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/kernel_iface.c b/src/kernel_iface.c
index e446102..98449b0 100644
--- a/src/kernel_iface.c
+++ b/src/kernel_iface.c
@@ -86,6 +86,7 @@ int init_kernel_iface(void)
 {
         int err = 0;
         long page_size = sysconf(_SC_PAGESIZE);
+        void* mapped_at = NULL;
 
         BUILD_BUG_ON(sizeof(union np_flag) != sizeof(uint64_t));
 
@@ -98,7 +99,13 @@ int init_kernel_iface(void)
         BUILD_BUG_ON(offsetof(struct control_page, irq_syscall_start)
                      != LITMUS_CP_OFFSET_IRQ_SC_START);
 
-        err = map_file(LITMUS_CTRL_DEVICE, (void**) &ctrl_page, CTRL_PAGES * page_size);
+        err = map_file(LITMUS_CTRL_DEVICE, &mapped_at, CTRL_PAGES * page_size);
+
+        /* Assign ctrl_page indirectly to avoid GCC warnings about aliasing
+         * related to type pruning.
+         */
+        ctrl_page = mapped_at;
+
         if (err) {
                 fprintf(stderr, "%s: cannot open LITMUS^RT control page (%m)\n",
                         __FUNCTION__);