uml: Create a private mount of proc for mconsole

The mconsole code only ever accesses proc for the initial pid
namespace.  Instead of depending upon the proc_mnt which is
for proc_flush_task have uml create it's own mount of proc
instead.

This allows proc_flush_task to evolve and remove the
need for having a proc_mnt to do it's job.

Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index e8f5c81c2c6c4ce917c1308abc4dcda75b24e38b..30575bd9297525400c4510f55eee038f6e7eb1ae 100644 (file)
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -36,6 +36,8 @@
 #include "mconsole_kern.h"
 #include <os.h>
 
+static struct vfsmount *proc_mnt = NULL;
+
 static int do_unlink_socket(struct notifier_block *notifier,
                            unsigned long what, void *data)
 {
@@ -123,7 +125,7 @@ void mconsole_log(struct mc_request *req)
 
 void mconsole_proc(struct mc_request *req)
 {
-       struct vfsmount *mnt = init_pid_ns.proc_mnt;
+       struct vfsmount *mnt = proc_mnt;
        char *buf;
        int len;
        struct file *file;
@@ -134,6 +136,10 @@ void mconsole_proc(struct mc_request *req)
        ptr += strlen("proc");
        ptr = skip_spaces(ptr);
 
+       if (!mnt) {
+               mconsole_reply(req, "Proc not available", 1, 0);
+               goto out;
+       }
        file = file_open_root(mnt->mnt_root, mnt, ptr, O_RDONLY, 0);
        if (IS_ERR(file)) {
                mconsole_reply(req, "Failed to open file", 1, 0);
@@ -683,6 +689,24 @@ void mconsole_stack(struct mc_request *req)
        with_console(req, stack_proc, to);
 }
 
+static int __init mount_proc(void)
+{
+       struct file_system_type *proc_fs_type;
+       struct vfsmount *mnt;
+
+       proc_fs_type = get_fs_type("proc");
+       if (!proc_fs_type)
+               return -ENODEV;
+
+       mnt = kern_mount(proc_fs_type);
+       put_filesystem(proc_fs_type);
+       if (IS_ERR(mnt))
+               return PTR_ERR(mnt);
+
+       proc_mnt = mnt;
+       return 0;
+}
+
 /*
  * Changed by mconsole_setup, which is __setup, and called before SMP is
  * active.
@@ -696,6 +720,8 @@ static int __init mconsole_init(void)
        int err;
        char file[UNIX_PATH_MAX];
 
+       mount_proc();
+
        if (umid_file_name("mconsole", file, sizeof(file)))
                return -1;
        snprintf(mconsole_socket_name, sizeof(file), "%s", file);