Messages in this thread Patch in this message | | | From | Chen LinX <> | Subject | [PATCH V2] debugfs: keep the old mode value at remount when no explicit change | Date | Fri, 29 Aug 2014 10:33:23 +0800 |
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From: "Chen, LinX" <linx.z.chen@intel.com>
Android framework has a good method to detect userspace hang and reports UIWDT issues. It uses client/server model. Clients communicate with servers by binder. binder has debugfs interfaces. Some files show what threads are communicating with what other threads. If one thread is blocked for a long time, we can find the blocking chain from the binder info. Since the error dumping process has no root access, booting process changes debugfs mount dir mode to 0755. When UIWDT happens, the error dumping process can read the info.
Unfortunately, some other scripts at booting try to mount debugfs for many times. No matter if the double mounting fails or succeeds, debugfs_parse_options changes the root inode's mode back to default 0700. It means the effect of previous mode changing to 0755 is lost. At UIWDT, the dumping process can't save binder info to disk log files.
The patch checks if debugfs_mount_opts->mode is initiated. If it is already, it bypasses the reinitiation, and the old mode value is kept.
Signed-off-by: He, Bo <bo.he@intel.com> Signed-off-by: Chen, LinX <linx.z.chen@intel.com> --- fs/debugfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index c7c83ff..f1eb4b9 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -159,7 +159,8 @@ static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts) kgid_t gid; char *p; - opts->mode = DEBUGFS_DEFAULT_MODE; + if (opts->mode == 0) + opts->mode = DEBUGFS_DEFAULT_MODE; while ((p = strsep(&data, ",")) != NULL) { if (!*p) -- 1.7.9.5
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