On 9/12/25 14:09, Daniel P. Berrangé wrote:
On Tue, Dec 09, 2025 at 02:03:27PM +0100, Philippe Mathieu-Daudé wrote:
On 9/12/25 13:50, Stefan Weil via wrote:
This fixes a compiler error when higher warning levels are enabled:
../migration/postcopy-ram.c: In function ‘postcopy_temp_pages_setup’:
../migration/postcopy-ram.c:1483:50: error: ‘g_malloc0_n’ sizes specified with
‘sizeof’ in the earlier argument and not in the later argument
[-Werror=calloc-transposed-args]
1483 | mis->postcopy_tmp_pages = g_malloc0_n(sizeof(PostcopyTmpPage),
channels);
| ^~~~~~~~~~~~~~~
../migration/postcopy-ram.c:1483:50: note: earlier argument should specify
number of elements, later size of each element
Avoid also a related int/unsigned mismatch by fixing the type of
two local variables.
Signed-off-by: Stefan Weil <[email protected]>
---
migration/postcopy-ram.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 3f98dcb6fd..8bef0192aa 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1467,7 +1467,8 @@ retry:
static int postcopy_temp_pages_setup(MigrationIncomingState *mis)
{
PostcopyTmpPage *tmp_page;
- int err, i, channels;
+ int err;
+ unsigned i, channels;
void *temp_page;
if (migrate_postcopy_preempt()) {
@@ -1479,7 +1480,7 @@ static int
postcopy_temp_pages_setup(MigrationIncomingState *mis)
}
channels = mis->postcopy_channels;
- mis->postcopy_tmp_pages = g_malloc0_n(sizeof(PostcopyTmpPage), channels);
+ mis->postcopy_tmp_pages = g_malloc0_n(channels, sizeof(PostcopyTmpPage));
I suppose we wanted to use:
g_new0(PostcopyTmpPage, channels)
What is the benefit of g_malloc0_n() over g_new0()?
g_malloc0_n should be used only in scenarios where you do NOT have a type
you can pass to g_new0. For example in the audio code
cap->buf = g_malloc0_n(hw->mix_buf.size, hw->info.bytes_per_frame);
any calls to g_malloc0_n which use sizeof(some-type) in an arg are
code style laws IMHO and should be changed to g_new0.
Or to put it another way. g_new0 must always be used/preferred except
in the handful of cases where it isn't possible.
Thanks (you confirmed my view).
Regards,
Phil.
