[Qemu-devel] [PATCH v2] oslib-posix: Fix compiler warning and some data types

[Stefan Weil]

gcc warning:

/qemu/util/oslib-posix.c:304:11: error:
 variable ‘addr’ might be clobbered by ‘longjmp’ or ‘vfork’
 [-Werror=clobbered]

Fix also some related data types:

numpages, hpagesize are used as pointer offset.
Always use size_t for them and for the derived numpages_per_thread.

Avoid a type cast by declaring addr volatile.

Signed-off-by: Stefan Weil <address@hidden>
---

v2: Fix more data types (partially as discussed with Richard)

Please note that checkpatch.pl raises an error:

ERROR: Use of volatile is usually wrong: see 
Documentation/volatile-considered-harmful.txt

This error is wrong in the current context.
It also refers to a file which exists in the Linux sources
but not in the QEMU source.

Regards
Stefan

 util/oslib-posix.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 80086c549f..beef148c96 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -59,8 +59,8 @@
 
 struct MemsetThread {
     char *addr;
-    uint64_t numpages;
-    uint64_t hpagesize;
+    size_t numpages;
+    size_t hpagesize;
     QemuThread pgthread;
     sigjmp_buf env;
 };
@@ -301,11 +301,7 @@ static void sigbus_handler(int signal)
 static void *do_touch_pages(void *arg)
 {
     MemsetThread *memset_args = (MemsetThread *)arg;
-    char *addr = memset_args->addr;
-    uint64_t numpages = memset_args->numpages;
-    uint64_t hpagesize = memset_args->hpagesize;
     sigset_t set, oldset;
-    int i = 0;
 
     /* unblock SIGBUS */
     sigemptyset(&set);
@@ -315,6 +311,10 @@ static void *do_touch_pages(void *arg)
     if (sigsetjmp(memset_args->env, 1)) {
         memset_thread_failed = true;
     } else {
+        volatile char *addr = memset_args->addr;
+        size_t numpages = memset_args->numpages;
+        size_t hpagesize = memset_args->hpagesize;
+        size_t i;
         for (i = 0; i < numpages; i++) {
             /*
              * Read & write back the same value, so we don't
@@ -328,7 +328,7 @@ static void *do_touch_pages(void *arg)
              * don't need to write at all so we don't cause
              * wear on the storage backing the region...
              */
-            *(volatile char *)addr = *addr;
+            *addr = *addr;
             addr += hpagesize;
         }
     }
@@ -351,7 +351,8 @@ static inline int get_memset_num_threads(int smp_cpus)
 static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
                             int smp_cpus)
 {
-    uint64_t numpages_per_thread, size_per_thread;
+    size_t numpages_per_thread;
+    size_t size_per_thread;
     char *addr = area;
     int i = 0;
 
-- 
2.11.0