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Date: Tue, 31 Jan 2012 20:50:44 +0800 From: Cong Wang <xiyou.wangcong@...il.com> To: linux-kernel@...r.kernel.org Cc: Andrew Morton <akpm@...ux-foundation.org>, WANG Cong <xiyou.wangcong@...il.com>, Al Viro <viro@...iv.linux.org.uk>, Vasiliy Kulikov <segoon@...nwall.com>, Stephen Wilson <wilsons@...rt.ca>, David Rientjes <rientjes@...gle.com> Subject: [PATCH] proc: clean up /proc/<pid>/environ handling Similar to commit e268337dfe26dfc7efd422a804dbb27977a3cccc (proc: clean up and fix /proc/<pid>/mem handling), move the check of permission to open(), this will simplify read() code. Signed-off-by: WANG Cong <xiyou.wangcong@...il.com> --- diff --git a/fs/proc/base.c b/fs/proc/base.c index 9cde9edf..3d30eb4 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -835,28 +835,38 @@ static const struct file_operations proc_mem_operations = { .release = mem_release, }; +static int environ_open(struct inode *inode, struct file *file) +{ + struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode); + struct mm_struct *mm; + + if (!task) + return -ESRCH; + + mm = mm_for_maps(task); + put_task_struct(task); + + if (!mm) + return -ENOENT; + if (IS_ERR(mm)) + return PTR_ERR(mm); + + file->private_data = mm; + + return 0; +} + static ssize_t environ_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { - struct task_struct *task = get_proc_task(file->f_dentry->d_inode); char *page; unsigned long src = *ppos; - int ret = -ESRCH; - struct mm_struct *mm; - - if (!task) - goto out_no_task; + int ret = 0; + struct mm_struct *mm = file->private_data; - ret = -ENOMEM; page = (char *)__get_free_page(GFP_TEMPORARY); if (!page) - goto out; - - - mm = mm_for_maps(task); - ret = PTR_ERR(mm); - if (!mm || IS_ERR(mm)) - goto out_free; + return -ENOMEM; ret = 0; while (count > 0) { @@ -870,7 +880,7 @@ static ssize_t environ_read(struct file *file, char __user *buf, max_len = (count > PAGE_SIZE) ? PAGE_SIZE : count; this_len = (this_len > max_len) ? max_len : this_len; - retval = access_process_vm(task, (mm->env_start + src), + retval = access_remote_vm(mm, (mm->env_start + src), page, this_len, 0); if (retval <= 0) { @@ -890,18 +900,23 @@ static ssize_t environ_read(struct file *file, char __user *buf, } *ppos = src; - mmput(mm); -out_free: free_page((unsigned long) page); -out: - put_task_struct(task); -out_no_task: return ret; } +static int environ_release(struct inode *inode, struct file *file) +{ + struct mm_struct *mm = file->private_data; + + mmput(mm); + return 0; +} + static const struct file_operations proc_environ_operations = { + .open = environ_open, .read = environ_read, .llseek = generic_file_llseek, + .release = environ_release, }; static ssize_t oom_adjust_read(struct file *file, char __user *buf, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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