[PATCH 4/4] binder: Add binder_proc logging to binderfs

From: Hridya Valsaraju
Date: Tue Aug 27 2019 - 16:42:34 EST

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@xxxxxxxxxx>
---
drivers/android/binder.c | 38 ++++++++++++++++++-
drivers/android/binder_internal.h | 46 ++++++++++++++++++++++
drivers/android/binderfs.c | 63 ++++++++++++++-----------------
3 files changed, 111 insertions(+), 36 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index bed217310197..37189838f32a 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 +5410,27 @@ 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 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;
+
+ }
+
return 0;
}

@@ -5442,6 +5470,12 @@ 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 dc25a7d759c9..c386a3738290 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;
@@ -535,7 +504,22 @@ static struct dentry *binderfs_create_dentry(struct dentry *dir,
return dentry;
}

-static struct dentry *binderfs_create_file(struct dentry *dir, const char *name,
+void binderfs_remove_file(struct dentry *dentry)
+{
+ struct inode *dir;
+
+ dir = d_inode(dentry->d_parent);
+ inode_lock(dir);
+ if (simple_positive(dentry)) {
+ dget(dentry);
+ simple_unlink(dir, dentry);
+ d_delete(dentry);
+ dput(dentry);
+ }
+ inode_unlock(dir);
+}
+
+struct dentry *binderfs_create_file(struct dentry *dir, const char *name,
const struct file_operations *fops,
void *data)
{
@@ -604,7 +588,8 @@ static struct dentry *binderfs_create_dir(struct dentry *parent,

static int init_binder_logs(struct super_block *sb)
{
- struct dentry *binder_logs_root_dir, *file_dentry;
+ struct dentry *binder_logs_root_dir, *file_dentry, *proc_log_dir;
+ struct binderfs_info *info;
int ret = 0;

binder_logs_root_dir = binderfs_create_dir(sb->s_root,
@@ -648,8 +633,18 @@ static int init_binder_logs(struct super_block *sb)
"failed_transaction_log",
&binder_transaction_log_fops,
&binder_transaction_log_failed);
- if (IS_ERR(file_dentry))
+ if (IS_ERR(file_dentry)) {
ret = PTR_ERR(file_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