On 15/03/2021 15.25, Markus Armbruster wrote:
Mahmoud, it's generally a good idea to cc: people who commented on a
previous iteration of the same patch. In this case, Thomas. I'm doing
that for you now.
Mahmoud Mandour <ma.mando...@gmail.com> writes:
On Mon, Mar 15, 2021 at 1:13 PM Philippe Mathieu-Daudé <phi...@redhat.com>
wrote:
Hi Mahmoud,
On 3/15/21 11:58 AM, Mahmoud Mandour wrote:
Replaced a call to malloc() and its respective call to free()
with g_malloc() and g_free().
g_malloc() is preferred more than g_try_* functions, which
return NULL on error, when the size of the requested
allocation is small. This is because allocating few
bytes should not be a problem in a healthy system.
Otherwise, the system is already in a critical state.
Subsequently, removed NULL-checking after g_malloc().
Signed-off-by: Mahmoud Mandour <ma.mando...@gmail.com>
---
util/compatfd.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/util/compatfd.c b/util/compatfd.c
index 174f394533..a8ec525c6c 100644
--- a/util/compatfd.c
+++ b/util/compatfd.c
@@ -72,14 +72,10 @@ static int qemu_signalfd_compat(const sigset_t *mask)
QemuThread thread;
int fds[2];
- info = malloc(sizeof(*info));
- if (info == NULL) {
- errno = ENOMEM;
- return -1;
- }
+ info = g_malloc(sizeof(*info));
Watch out...
https://developer.gnome.org/glib/stable/glib-Memory-Allocation.html
If any call to allocate memory using functions g_new(), g_new0(),
g_renew(), g_malloc(), g_malloc0(), g_malloc0_n(), g_realloc(),
and g_realloc_n() fails, the application is terminated.
So with your change instead of handling ENOMEM the QEMU process is
simply killed.
Don't you want to use g_try_new(struct sigfd_compat_info, 1) here
instead?
if (pipe(fds) == -1) {
- free(info);
+ g_free(info);
return -1;
}
Hello Mr. Philippe,
That's originally what I did and I sent a patch that uses a g_try_*
variant, and was
instructed by Mr. Thomas Huth that it was better to use g_malloc instead
No need to say "Mr." here ... we're not that formal on this mailing list
here :-)
because this is a small allocation and the process is better killed if such
an allocation fails because the system is already in a very critical state
if it does not handle a small allocation well.
You even explained this in the commit message. Appreciated.
You can find Mr. Thomas reply to my previous patch here:
Re: [PATCH 5/8] util/compatfd.c: Replaced a malloc with GLib's variant
(gnu.org)
<https://lists.gnu.org/archive/html/qemu-devel/2021-03/msg05067.html>
You can instruct me on what to do further.
I figure this patch is fine. Thomas?
Yes, looks good now, thanks for the update, Mahmoud!
Reviewed-by: Thomas Huth <th...@redhat.com>
