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SubjectRe: [PATCH v2 4/4] binder: Add binder_proc logging to binderfs
On Thu, Aug 29, 2019 at 02:18:12PM -0700, Hridya Valsaraju wrote:
> Currently /sys/kernel/debug/binder/proc contains
> the debug data for every binder_proc instance.
> This patch makes this information also available
> in a binderfs instance mounted with a mount option
> "stats=global" in addition to debugfs. The patch does
> not affect the presence of the file in debugfs.
>
> If a binderfs instance is mounted at path /dev/binderfs,
> this file would be present at /dev/binderfs/binder_logs/proc.
> This change provides an alternate way to access this file when debugfs
> is not mounted.
>
> Signed-off-by: Hridya Valsaraju <hridya@google.com>

Same as for the previous patch: Please keep my Acked-by if you don't
change this patch when you send out a new version.

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

> ---
>
> Changes in v2:
> - Consistent variable naming across functions as per Christian
> Brauner.
> - As suggested by Todd Kjos, log a failure to create a
> process-specific binderfs log file if the error code is not EEXIST
> since an error code of EEXIST is expected if
> multiple contexts of the same process try to create the file during
> binder_open().
>
> drivers/android/binder.c | 46 ++++++++++++++++++++-
> drivers/android/binder_internal.h | 46 +++++++++++++++++++++
> drivers/android/binderfs.c | 68 ++++++++++++++-----------------
> 3 files changed, 121 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index bed217310197..ee610ea48309 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -481,6 +481,7 @@ struct binder_priority {
> * @inner_lock: can nest under outer_lock and/or node lock
> * @outer_lock: no nesting under innor or node lock
> * Lock order: 1) outer, 2) node, 3) inner
> + * @binderfs_entry: process-specific binderfs log file
> *
> * Bookkeeping structure for binder processes
> */
> @@ -510,6 +511,7 @@ struct binder_proc {
> struct binder_context *context;
> spinlock_t inner_lock;
> spinlock_t outer_lock;
> + struct dentry *binderfs_entry;
> };
>
> enum {
> @@ -5347,6 +5349,8 @@ static int binder_open(struct inode *nodp, struct file *filp)
> {
> struct binder_proc *proc;
> struct binder_device *binder_dev;
> + struct binderfs_info *info;
> + struct dentry *binder_binderfs_dir_entry_proc = NULL;
>
> binder_debug(BINDER_DEBUG_OPEN_CLOSE, "%s: %d:%d\n", __func__,
> current->group_leader->pid, current->pid);
> @@ -5368,11 +5372,14 @@ static int binder_open(struct inode *nodp, struct file *filp)
> }
>
> /* binderfs stashes devices in i_private */
> - if (is_binderfs_device(nodp))
> + if (is_binderfs_device(nodp)) {
> binder_dev = nodp->i_private;
> - else
> + info = nodp->i_sb->s_fs_info;
> + binder_binderfs_dir_entry_proc = info->proc_log_dir;
> + } else {
> binder_dev = container_of(filp->private_data,
> struct binder_device, miscdev);
> + }
> proc->context = &binder_dev->context;
> binder_alloc_init(&proc->alloc);
>
> @@ -5403,6 +5410,35 @@ static int binder_open(struct inode *nodp, struct file *filp)
> &proc_fops);
> }
>
> + if (binder_binderfs_dir_entry_proc) {
> + char strbuf[11];
> + struct dentry *binderfs_entry;
> +
> + snprintf(strbuf, sizeof(strbuf), "%u", proc->pid);
> + /*
> + * Similar to debugfs, the process specific log file is shared
> + * between contexts. If the file has already been created for a
> + * process, the following binderfs_create_file() call will
> + * fail with error code EEXIST if another context of the same
> + * process invoked binder_open(). This is ok since same as
> + * debugfs, the log file will contain information on all
> + * contexts of a given PID.
> + */
> + binderfs_entry = binderfs_create_file(binder_binderfs_dir_entry_proc,
> + strbuf, &proc_fops, (void *)(unsigned long)proc->pid);
> + if (!IS_ERR(binderfs_entry)) {
> + proc->binderfs_entry = binderfs_entry;
> + } else {
> + int error;
> +
> + error = PTR_ERR(binderfs_entry);
> + if (error != -EEXIST) {
> + pr_warn("Unable to create file %s in binderfs (error %d)\n",
> + strbuf, error);
> + }
> + }
> + }
> +
> return 0;
> }
>
> @@ -5442,6 +5478,12 @@ static int binder_release(struct inode *nodp, struct file *filp)
> struct binder_proc *proc = filp->private_data;
>
> debugfs_remove(proc->debugfs_entry);
> +
> + if (proc->binderfs_entry) {
> + binderfs_remove_file(proc->binderfs_entry);
> + proc->binderfs_entry = NULL;
> + }
> +
> binder_defer_work(proc, BINDER_DEFERRED_RELEASE);
>
> return 0;
> diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h
> index b9be42d9464c..bd47f7f72075 100644
> --- a/drivers/android/binder_internal.h
> +++ b/drivers/android/binder_internal.h
> @@ -35,17 +35,63 @@ struct binder_device {
> struct inode *binderfs_inode;
> };
>
> +/**
> + * binderfs_mount_opts - mount options for binderfs
> + * @max: maximum number of allocatable binderfs binder devices
> + * @stats_mode: enable binder stats in binderfs.
> + */
> +struct binderfs_mount_opts {
> + int max;
> + int stats_mode;
> +};
> +
> +/**
> + * binderfs_info - information about a binderfs mount
> + * @ipc_ns: The ipc namespace the binderfs mount belongs to.
> + * @control_dentry: This records the dentry of this binderfs mount
> + * binder-control device.
> + * @root_uid: uid that needs to be used when a new binder device is
> + * created.
> + * @root_gid: gid that needs to be used when a new binder device is
> + * created.
> + * @mount_opts: The mount options in use.
> + * @device_count: The current number of allocated binder devices.
> + * @proc_log_dir: Pointer to the directory dentry containing process-specific
> + * logs.
> + */
> +struct binderfs_info {
> + struct ipc_namespace *ipc_ns;
> + struct dentry *control_dentry;
> + kuid_t root_uid;
> + kgid_t root_gid;
> + struct binderfs_mount_opts mount_opts;
> + int device_count;
> + struct dentry *proc_log_dir;
> +};
> +
> 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);
> +extern struct dentry *binderfs_create_file(struct dentry *dir, const char *name,
> + const struct file_operations *fops,
> + void *data);
> +extern void binderfs_remove_file(struct dentry *dentry);
> #else
> static inline bool is_binderfs_device(const struct inode *inode)
> {
> return false;
> }
> +static inline struct dentry *binderfs_create_file(struct dentry *dir,
> + const char *name,
> + const struct file_operations *fops,
> + void *data)
> +{
> + return NULL;
> +}
> +static inline void binderfs_remove_file(struct dentry *dentry) {}
> #endif
>
> #ifdef CONFIG_ANDROID_BINDERFS
> diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
> index 1715e72ce9c7..d6b50fe38218 100644
> --- a/drivers/android/binderfs.c
> +++ b/drivers/android/binderfs.c
> @@ -48,16 +48,6 @@ static dev_t binderfs_dev;
> static DEFINE_MUTEX(binderfs_minors_mutex);
> static DEFINE_IDA(binderfs_minors);
>
> -/**
> - * binderfs_mount_opts - mount options for binderfs
> - * @max: maximum number of allocatable binderfs binder devices
> - * @stats_mode: enable binder stats in binderfs.
> - */
> -struct binderfs_mount_opts {
> - int max;
> - int stats_mode;
> -};
> -
> enum {
> Opt_max,
> Opt_stats_mode,
> @@ -75,27 +65,6 @@ static const match_table_t tokens = {
> { Opt_err, NULL }
> };
>
> -/**
> - * binderfs_info - information about a binderfs mount
> - * @ipc_ns: The ipc namespace the binderfs mount belongs to.
> - * @control_dentry: This records the dentry of this binderfs mount
> - * binder-control device.
> - * @root_uid: uid that needs to be used when a new binder device is
> - * created.
> - * @root_gid: gid that needs to be used when a new binder device is
> - * created.
> - * @mount_opts: The mount options in use.
> - * @device_count: The current number of allocated binder devices.
> - */
> -struct binderfs_info {
> - struct ipc_namespace *ipc_ns;
> - struct dentry *control_dentry;
> - kuid_t root_uid;
> - kgid_t root_gid;
> - struct binderfs_mount_opts mount_opts;
> - int device_count;
> -};
> -
> static inline struct binderfs_info *BINDERFS_I(const struct inode *inode)
> {
> return inode->i_sb->s_fs_info;
> @@ -533,10 +502,24 @@ static struct dentry *binderfs_create_dentry(struct dentry *parent,
> return dentry;
> }
>
> -static struct dentry *binderfs_create_file(struct dentry *parent,
> - const char *name,
> - const struct file_operations *fops,
> - void *data)
> +void binderfs_remove_file(struct dentry *dentry)
> +{
> + struct inode *parent_inode;
> +
> + parent_inode = d_inode(dentry->d_parent);
> + inode_lock(parent_inode);
> + if (simple_positive(dentry)) {
> + dget(dentry);
> + simple_unlink(parent_inode, dentry);
> + d_delete(dentry);
> + dput(dentry);
> + }
> + inode_unlock(parent_inode);
> +}
> +
> +struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
> + const struct file_operations *fops,
> + void *data)
> {
> struct dentry *dentry;
> struct inode *new_inode, *parent_inode;
> @@ -604,7 +587,8 @@ static struct dentry *binderfs_create_dir(struct dentry *parent,
>
> static int init_binder_logs(struct super_block *sb)
> {
> - struct dentry *binder_logs_root_dir, *dentry;
> + struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
> + struct binderfs_info *info;
> int ret = 0;
>
> binder_logs_root_dir = binderfs_create_dir(sb->s_root,
> @@ -648,8 +632,18 @@ static int init_binder_logs(struct super_block *sb)
> "failed_transaction_log",
> &binder_transaction_log_fops,
> &binder_transaction_log_failed);
> - if (IS_ERR(dentry))
> + if (IS_ERR(dentry)) {
> ret = PTR_ERR(dentry);
> + goto out;
> + }
> +
> + proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
> + if (IS_ERR(proc_log_dir)) {
> + ret = PTR_ERR(proc_log_dir);
> + goto out;
> + }
> + info = sb->s_fs_info;
> + info->proc_log_dir = proc_log_dir;
>
> out:
> return ret;
> --
> 2.23.0.187.g17f5b7556c-goog
>

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