TechPanelGM/kernel_xiaomi_sm8250
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

UPSTREAM: binderfs: reserve devices for initial mount

Browse Source 
The binderfs instance in the initial ipc namespace will always have a
reserve of 4 binder devices unless explicitly capped by specifying a lower
value via the "max" mount option.
This ensures when binder devices are removed (on accident or on purpose)
they can always be recreated without risking that all minor numbers have
already been used up.

Cc: Todd Kjos <tkjos@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 136497735
(cherry picked from commit 36bdf3cae09df891b191f3955c8e54a2e05d67d0)
Change-Id: I001f305659c37e3b631696712332ae2e21464be8
Signed-off-by: Hridya Valsaraju <hridya@google.com>
This commit is contained in:
Christian Brauner
2019-01-11 11:19:40 +01:00
committed by Hridya Valsaraju
parent a482713b5a
commit cbfaab8aa3
1 changed files with 6 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/android/binderfs.c
View File

@@ -40,6 +40,8 @@
#define INODE_OFFSET 3
#define INTSTRLEN 21
#define BINDERFS_MAX_MINOR (1U << MINORBITS)
/* Ensure that the initial ipc namespace always has devices available. */
#define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
static dev_t binderfs_dev;
static DEFINE_MUTEX(binderfs_minors_mutex);
@@ -127,11 +129,14 @@ static int binderfs_binder_device_create(struct inode *ref_inode,
struct inode *inode = NULL;
struct super_block *sb = ref_inode->i_sb;
struct binderfs_info *info = sb->s_fs_info;
bool use_reserve = (info->ipc_ns == &init_ipc_ns);
/* Reserve new minor number for the new device. */
mutex_lock(&binderfs_minors_mutex);
if (++info->device_count <= info->mount_opts.max)
minor = ida_alloc_max(&binderfs_minors, BINDERFS_MAX_MINOR,
minor = ida_alloc_max(&binderfs_minors,
use_reserve ? BINDERFS_MAX_MINOR :
BINDERFS_MAX_MINOR_CAPPED,
GFP_KERNEL);
else
minor = -ENOSPC;