rcu: Changes from reviews: avoid casts, fix/add warnings, improve comments

[safe/jmp/linux-2.6] / fs / proc / base.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index aef6d55..175db25 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -80,6 +80,7 @@
 #include <linux/oom.h>
 #include <linux/elf.h>
 #include <linux/pid_namespace.h>
+#include <linux/fs_struct.h>
 #include "internal.h"
 
 /* NOTE:
@@ -146,15 +147,22 @@ static unsigned int pid_entry_count_dirs(const struct pid_entry *entries,
        return count;
 }
 
-static struct fs_struct *get_fs_struct(struct task_struct *task)
+static int get_fs_path(struct task_struct *task, struct path *path, bool root)
 {
        struct fs_struct *fs;
+       int result = -ENOENT;
+
        task_lock(task);
        fs = task->fs;
-       if(fs)
-               atomic_inc(&fs->count);
+       if (fs) {
+               read_lock(&fs->lock);
+               *path = root ? fs->root : fs->pwd;
+               path_get(path);
+               read_unlock(&fs->lock);
+               result = 0;
+       }
        task_unlock(task);
-       return fs;
+       return result;
 }
 
 static int get_nr_threads(struct task_struct *tsk)
@@ -172,42 +180,24 @@ static int get_nr_threads(struct task_struct *tsk)
 static int proc_cwd_link(struct inode *inode, struct path *path)
 {
        struct task_struct *task = get_proc_task(inode);
-       struct fs_struct *fs = NULL;
        int result = -ENOENT;
 
        if (task) {
-               fs = get_fs_struct(task);
+               result = get_fs_path(task, path, 0);
                put_task_struct(task);
        }
-       if (fs) {
-               read_lock(&fs->lock);
-               *path = fs->pwd;
-               path_get(&fs->pwd);
-               read_unlock(&fs->lock);
-               result = 0;
-               put_fs_struct(fs);
-       }
        return result;
 }
 
 static int proc_root_link(struct inode *inode, struct path *path)
 {
        struct task_struct *task = get_proc_task(inode);
-       struct fs_struct *fs = NULL;
        int result = -ENOENT;
 
        if (task) {
-               fs = get_fs_struct(task);
+               result = get_fs_path(task, path, 1);
                put_task_struct(task);
        }
-       if (fs) {
-               read_lock(&fs->lock);
-               *path = fs->root;
-               path_get(&fs->root);
-               read_unlock(&fs->lock);
-               result = 0;
-               put_fs_struct(fs);
-       }
        return result;
 }
 
@@ -244,23 +234,20 @@ static int check_mem_permission(struct task_struct *task)
 
 struct mm_struct *mm_for_maps(struct task_struct *task)
 {
-       struct mm_struct *mm = get_task_mm(task);
-       if (!mm)
+       struct mm_struct *mm;
+
+       if (mutex_lock_killable(&task->cred_guard_mutex))
                return NULL;
-       down_read(&mm->mmap_sem);
-       task_lock(task);
-       if (task->mm != mm)
-               goto out;
-       if (task->mm != current->mm &&
-           __ptrace_may_access(task, PTRACE_MODE_READ) < 0)
-               goto out;
-       task_unlock(task);
+
+       mm = get_task_mm(task);
+       if (mm && mm != current->mm &&
+                       !ptrace_may_access(task, PTRACE_MODE_READ)) {
+               mmput(mm);
+               mm = NULL;
+       }
+       mutex_unlock(&task->cred_guard_mutex);
+
        return mm;
-out:
-       task_unlock(task);
-       up_read(&mm->mmap_sem);
-       mmput(mm);
-       return NULL;
 }
 
 static int proc_pid_cmdline(struct task_struct *task, char * buffer)
@@ -332,7 +319,10 @@ static int proc_pid_wchan(struct task_struct *task, char *buffer)
        wchan = get_wchan(task);
 
        if (lookup_symbol_name(wchan, symname) < 0)
-               return sprintf(buffer, "%lu", wchan);
+               if (!ptrace_may_access(task, PTRACE_MODE_READ))
+                       return 0;
+               else
+                       return sprintf(buffer, "%lu", wchan);
        else
                return sprintf(buffer, "%s", symname);
 }
@@ -596,7 +586,6 @@ static int mounts_open_common(struct inode *inode, struct file *file,
        struct task_struct *task = get_proc_task(inode);
        struct nsproxy *nsp;
        struct mnt_namespace *ns = NULL;
-       struct fs_struct *fs = NULL;
        struct path root;
        struct proc_mounts *p;
        int ret = -EINVAL;
@@ -610,22 +599,16 @@ static int mounts_open_common(struct inode *inode, struct file *file,
                                get_mnt_ns(ns);
                }
                rcu_read_unlock();
-               if (ns)
-                       fs = get_fs_struct(task);
+               if (ns && get_fs_path(task, &root, 1) == 0)
+                       ret = 0;
                put_task_struct(task);
        }
 
        if (!ns)
                goto err;
-       if (!fs)
+       if (ret)
                goto err_put_ns;
 
-       read_lock(&fs->lock);
-       root = fs->root;
-       path_get(&root);
-       read_unlock(&fs->lock);
-       put_fs_struct(fs);
-
        ret = -ENOMEM;
        p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
        if (!p)
@@ -665,14 +648,14 @@ static unsigned mounts_poll(struct file *file, poll_table *wait)
 {
        struct proc_mounts *p = file->private_data;
        struct mnt_namespace *ns = p->ns;
-       unsigned res = 0;
+       unsigned res = POLLIN | POLLRDNORM;
 
        poll_wait(file, &ns->poll, wait);
 
        spin_lock(&vfsmount_lock);
        if (p->event != ns->event) {
                p->event = ns->event;
-               res = POLLERR;
+               res |= POLLERR | POLLPRI;
        }
        spin_unlock(&vfsmount_lock);
 
@@ -1020,7 +1003,12 @@ static ssize_t oom_adjust_read(struct file *file, char __user *buf,
 
        if (!task)
                return -ESRCH;
-       oom_adjust = task->oomkilladj;
+       task_lock(task);
+       if (task->mm)
+               oom_adjust = task->mm->oom_adj;
+       else
+               oom_adjust = OOM_DISABLE;
+       task_unlock(task);
        put_task_struct(task);
 
        len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
@@ -1049,11 +1037,19 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
        task = get_proc_task(file->f_path.dentry->d_inode);
        if (!task)
                return -ESRCH;
-       if (oom_adjust < task->oomkilladj && !capable(CAP_SYS_RESOURCE)) {
+       task_lock(task);
+       if (!task->mm) {
+               task_unlock(task);
+               put_task_struct(task);
+               return -EINVAL;
+       }
+       if (oom_adjust < task->mm->oom_adj && !capable(CAP_SYS_RESOURCE)) {
+               task_unlock(task);
                put_task_struct(task);
                return -EACCES;
        }
-       task->oomkilladj = oom_adjust;
+       task->mm->oom_adj = oom_adjust;
+       task_unlock(task);
        put_task_struct(task);
        if (end - buffer == 0)
                return -EIO;
@@ -1970,7 +1966,7 @@ static struct dentry *proc_pident_instantiate(struct inode *dir,
        const struct pid_entry *p = ptr;
        struct inode *inode;
        struct proc_inode *ei;
-       struct dentry *error = ERR_PTR(-EINVAL);
+       struct dentry *error = ERR_PTR(-ENOENT);
 
        inode = proc_pid_make_inode(dir->i_sb, task);
        if (!inode)
@@ -2142,9 +2138,15 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
        if (copy_from_user(page, buf, count))
                goto out_free;
 
+       /* Guard against adverse ptrace interaction */
+       length = mutex_lock_interruptible(&task->cred_guard_mutex);
+       if (length < 0)
+               goto out_free;
+
        length = security_setprocattr(task,
                                      (char*)file->f_path.dentry->d_name.name,
                                      (void*)page, count);
+       mutex_unlock(&task->cred_guard_mutex);
 out_free:
        free_page((unsigned long) page);
 out: