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SubjectRe: [PATCH v3 1/2] binder: Add default binder devices through binderfs when configured
On Thu, Aug 08, 2019 at 03:27:25PM -0700, Hridya Valsaraju wrote:
> Currently, since each binderfs instance needs its own
> private binder devices, every time a binderfs instance is
> mounted, all the default binder devices need to be created
> via the BINDER_CTL_ADD IOCTL. This patch aims to
> add a solution to automatically create the default binder
> devices for each binderfs instance that gets mounted.
> To achieve this goal, when CONFIG_ANDROID_BINDERFS is set,
> the default binder devices specified by CONFIG_ANDROID_BINDER_DEVICES
> are created in each binderfs instance instead of global devices
> being created by the binder driver.
>
> Co-developed-by: Christian Brauner <christian.brauner@ubuntu.com>
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> Signed-off-by: Hridya Valsaraju <hridya@google.com>
> ---

Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>

thanks,

- Joel

>
> Changes in v2:
> - Updated commit message as per Greg Kroah-Hartman.
> - Removed new module parameter creation as per Greg
> Kroah-Hartman/Christian Brauner.
> - Refactored device name length check into a new patch as per Greg Kroah-Hartman.
>
> Changes in v3:
> -Removed unnecessary empty lines as per Dan Carpenter.
>
> drivers/android/binder.c | 5 +++--
> drivers/android/binder_internal.h | 2 ++
> drivers/android/binderfs.c | 23 ++++++++++++++++++++---
> 3 files changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 466b6a7f8ab7..ca6b21a53321 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -123,7 +123,7 @@ static uint32_t binder_debug_mask = BINDER_DEBUG_USER_ERROR |
> BINDER_DEBUG_FAILED_TRANSACTION | BINDER_DEBUG_DEAD_TRANSACTION;
> module_param_named(debug_mask, binder_debug_mask, uint, 0644);
>
> -static char *binder_devices_param = CONFIG_ANDROID_BINDER_DEVICES;
> +char *binder_devices_param = CONFIG_ANDROID_BINDER_DEVICES;
> module_param_named(devices, binder_devices_param, charp, 0444);
>
> static DECLARE_WAIT_QUEUE_HEAD(binder_user_error_wait);
> @@ -6279,7 +6279,8 @@ static int __init binder_init(void)
> &transaction_log_fops);
> }
>
> - if (strcmp(binder_devices_param, "") != 0) {
> + if (!IS_ENABLED(CONFIG_ANDROID_BINDERFS) &&
> + strcmp(binder_devices_param, "") != 0) {
> /*
> * Copy the module_parameter string, because we don't want to
> * tokenize it in-place.
> diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h
> index 045b3e42d98b..fe8c745dc8e0 100644
> --- a/drivers/android/binder_internal.h
> +++ b/drivers/android/binder_internal.h
> @@ -37,6 +37,8 @@ struct binder_device {
>
> extern const struct file_operations binder_fops;
>
> +extern char *binder_devices_param;
> +
> #ifdef CONFIG_ANDROID_BINDERFS
> extern bool is_binderfs_device(const struct inode *inode);
> #else
> diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
> index e773f45d19d9..aee46dd1be91 100644
> --- a/drivers/android/binderfs.c
> +++ b/drivers/android/binderfs.c
> @@ -186,8 +186,7 @@ static int binderfs_binder_device_create(struct inode *ref_inode,
> req->major = MAJOR(binderfs_dev);
> req->minor = minor;
>
> - ret = copy_to_user(userp, req, sizeof(*req));
> - if (ret) {
> + if (userp && copy_to_user(userp, req, sizeof(*req))) {
> ret = -EFAULT;
> goto err;
> }
> @@ -467,6 +466,9 @@ static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
> int ret;
> struct binderfs_info *info;
> struct inode *inode = NULL;
> + struct binderfs_device device_info = { 0 };
> + const char *name;
> + size_t len;
>
> sb->s_blocksize = PAGE_SIZE;
> sb->s_blocksize_bits = PAGE_SHIFT;
> @@ -521,7 +523,22 @@ static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
> if (!sb->s_root)
> return -ENOMEM;
>
> - return binderfs_binder_ctl_create(sb);
> + ret = binderfs_binder_ctl_create(sb);
> + if (ret)
> + return ret;
> +
> + name = binder_devices_param;
> + for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
> + strscpy(device_info.name, name, len + 1);
> + ret = binderfs_binder_device_create(inode, NULL, &device_info);
> + if (ret)
> + return ret;
> + name += len;
> + if (*name == ',')
> + name++;
> + }
> +
> + return 0;
> }
>
> static struct dentry *binderfs_mount(struct file_system_type *fs_type,
> --
> 2.22.0.770.g0f2c4a37fd-goog
>

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