Re: [PATCH v2 4/5] plugins/loader: fix uninitialized variable warning in plugin_reset_uninstall()

[Alex Bennée]

Chen Qun <kuhn.chenqun@huawei.com> writes:

> After the WITH_QEMU_LOCK_GUARD macro is added, the compiler cannot identify
>  that the statements in the macro must be executed. As a result, some 
> variables
>  assignment statements in the macro may be considered as unexecuted by the 
> compiler.
>
> When the -Wmaybe-uninitialized capability is enabled on GCC9,the compiler 
> showed warning:
> plugins/loader.c: In function ‘plugin_reset_uninstall’:
> plugins/loader.c:382:15: warning: ‘ctx’ may be used uninitialized in this 
> function [-Wmaybe-uninitialized]
>  382 |     data->ctx = ctx;
>      |     ~~~~~~~~~~^~~~~
>
> Add a default value for 'expire_time' to prevented the warning.
>
> Reported-by: Euler Robot <euler.robot@huawei.com>
> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
> ---
> Cc: "Alex Bennée" <alex.bennee@linaro.org>
> ---
>  plugins/loader.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/plugins/loader.c b/plugins/loader.c
> index 8ac5dbc20f..88593fe138 100644
> --- a/plugins/loader.c
> +++ b/plugins/loader.c
> @@ -367,7 +367,7 @@ void plugin_reset_uninstall(qemu_plugin_id_t id,
>                              bool reset)
>  {
>      struct qemu_plugin_reset_data *data;
> -    struct qemu_plugin_ctx *ctx;
> +    struct qemu_plugin_ctx *ctx = NULL;

This doesn't really fix anything because you would end up faulting if
you attempted to de-ref a NULL ctx. However...

>  
>      WITH_QEMU_LOCK_GUARD(&plugin.lock) {
>          ctx = plugin_id_to_ctx_locked(id);

...this can't fail. If the lookup failed and returned a NULL plugin then
we would abort(). So why can't the Euler Robot see that?

-- 
Alex Bennée