diff options
| author | Mike Christie <michael.christie@oracle.com> | 2023-03-10 16:03:27 -0600 |
|---|---|---|
| committer | Christian Brauner (Microsoft) <brauner@kernel.org> | 2023-03-12 10:54:43 +0100 |
| commit | 11f3f500ec8a75c96087f3bed87aa2b1c5de7498 (patch) | |
| tree | 08d3834456a1139b1a6a3f059d13713bc8c268e2 /kernel/fork.c | |
| parent | 54e6842d0775ba76db65cbe21311c3ca466e663d (diff) | |
| download | linux-11f3f500ec8a75c96087f3bed87aa2b1c5de7498.tar.gz | |
fork: add kernel_clone_args flag to not dup/clone files
Each vhost device gets a thread that is used to perform IO and management
operations. Instead of a thread that is accessing a device, the thread is
part of the device, so when it creates a thread using a helper based on
copy_process we can't dup or clone the parent's files/FDS because it
would do an extra increment on ourself.
Later, when we do:
Qemu process exits:
do_exit -> exit_files -> put_files_struct -> close_files
we would leak the device's resources because of that extra refcount
on the fd or file_struct.
This patch adds a no_files option so these worker threads can prevent
taking an extra refcount on themselves.
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index fb8ec192c199..f8d530f4406e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1627,7 +1627,8 @@ static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) return 0; } -static int copy_files(unsigned long clone_flags, struct task_struct *tsk) +static int copy_files(unsigned long clone_flags, struct task_struct *tsk, + int no_files) { struct files_struct *oldf, *newf; int error = 0; @@ -1639,6 +1640,11 @@ static int copy_files(unsigned long clone_flags, struct task_struct *tsk) if (!oldf) goto out; + if (no_files) { + tsk->files = NULL; + goto out; + } + if (clone_flags & CLONE_FILES) { atomic_inc(&oldf->count); goto out; @@ -2259,7 +2265,7 @@ static __latent_entropy struct task_struct *copy_process( retval = copy_semundo(clone_flags, p); if (retval) goto bad_fork_cleanup_security; - retval = copy_files(clone_flags, p); + retval = copy_files(clone_flags, p, args->no_files); if (retval) goto bad_fork_cleanup_semundo; retval = copy_fs(clone_flags, p); |