Re: [PATCH v3 6/7] qga/commands-posix: don't do fork()/exec() when suspending via sysfs

[Andrey Drobyshev]

On 3/19/24 20:02, Daniel P. Berrangé wrote:
> On Fri, Mar 15, 2024 at 02:29:45PM +0200, Andrey Drobyshev wrote:
>> Since commit 246d76eba ("qga: guest_suspend: decoupling pm-utils and sys
>> logic") pm-utils logic is running in a separate child from the sysfs
>> logic.  Now when suspending via sysfs we don't really need to do that in
>> a separate process as we only need to perform one write to /sys/power/state.
>>
>> Let's just use g_file_set_contents() to simplify things here.
>>
>> Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
>> Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
>> ---
>>  qga/commands-posix.c | 41 +++++------------------------------------
>>  1 file changed, 5 insertions(+), 36 deletions(-)
> 
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> 
>>
>> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
>> index 610d225d30..e0ea377f65 100644
>> --- a/qga/commands-posix.c
>> +++ b/qga/commands-posix.c
>> @@ -1928,52 +1928,21 @@ static bool 
>> linux_sys_state_supports_mode(SuspendMode mode, Error **errp)
>>  
>>  static void linux_sys_state_suspend(SuspendMode mode, Error **errp)
>>  {
>> -    Error *local_err = NULL;
>> +    GError *local_gerr = NULL;
>>      const char *sysfile_strs[3] = {"disk", "mem", NULL};
>>      const char *sysfile_str = sysfile_strs[mode];
>> -    pid_t pid;
>> -    int status;
>>  
>>      if (!sysfile_str) {
>>          error_setg(errp, "unknown guest suspend mode");
>>          return;
>>      }
>>  
>> -    pid = fork();
>> -    if (!pid) {
>> -        /* child */
>> -        int fd;
>> -
>> -        setsid();
>> -        reopen_fd_to_null(0);
>> -        reopen_fd_to_null(1);
>> -        reopen_fd_to_null(2);
>> -
>> -        fd = open(LINUX_SYS_STATE_FILE, O_WRONLY);
>> -        if (fd < 0) {
>> -            _exit(EXIT_FAILURE);
>> -        }
>> -
>> -        if (write(fd, sysfile_str, strlen(sysfile_str)) < 0) {
>> -            _exit(EXIT_FAILURE);
>> -        }
>> -
>> -        _exit(EXIT_SUCCESS);
>> -    } else if (pid < 0) {
>> -        error_setg_errno(errp, errno, "failed to create child process");
>> -        return;
>> -    }
>> -
>> -    ga_wait_child(pid, &status, &local_err);
>> -    if (local_err) {
>> -        error_propagate(errp, local_err);
>> +    if (!g_file_set_contents(LINUX_SYS_STATE_FILE, sysfile_str,
>> +                             -1, &local_gerr)) {
>> +        error_setg(errp, "suspend: cannot write to '%s': %s",
>> +                   LINUX_SYS_STATE_FILE, local_gerr->message);
> 
> You need to declare with "g_autoptr(GError) local_gerr = NULL" to
> avoid a leak here.
> 

Of course, thanks for noticing.

>>          return;
>>      }
>> -
>> -    if (WEXITSTATUS(status)) {
>> -        error_setg(errp, "child process has failed to suspend");
>> -    }
>> -
>>  }
>>  
>>  static void guest_suspend(SuspendMode mode, Error **errp)
>> -- 
>> 2.39.3
>>
> 
> With regards,
> Daniel