[Stable-8.1.2 59/61] util/log: re-allow switching away from stderr log file

[Michael Tokarev]

From: Fiona Ebner <f.ebner@proxmox.com>

Commit 59bde21374 ("util/log: do not close and reopen log files when
flags are turned off") prevented switching away from stderr on a
subsequent invocation of qemu_set_log_internal(). This prevented
switching away from stderr with the 'logfile' monitor command as well
as an invocation like
> ./qemu-system-x86_64 -trace 'qemu_mutex_lock,file=log'
from opening the specified log file.

Fixes: 59bde21374 ("util/log: do not close and reopen log files when flags are 
turned off")
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231004124446.491481-1-f.ebner@proxmox.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit f05142d511e86d8e97967d21f205d990dfc634de)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/util/log.c b/util/log.c
index def88a9402..d36c98da0b 100644
--- a/util/log.c
+++ b/util/log.c
@@ -298,6 +298,8 @@ static bool qemu_set_log_internal(const char *filename, 
bool changed_name,
             r->fd = logfile;
             qatomic_rcu_set(&global_file, NULL);
             call_rcu(r, rcu_close_file, rcu);
+        }
+        if (changed_name) {
             logfile = NULL;
         }
     }
-- 
2.39.2