linux-kernel - Re: [PATCH v2] sparse: fix incorrect fmode

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Message-ID: <YoTzGfqtbt1Bvemj@infradead.org>
Date:   Wed, 18 May 2022 06:22:33 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Vasily Averin <vvs@...nvz.org>
Cc:     Christoph Hellwig <hch@...radead.org>, Jan Kara <jack@...e.cz>,
        Christian Brauner <brauner@...nel.org>, kernel@...nvz.org,
        linux-kernel@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Amir Goldstein <amir73il@...il.com>,
        Matthew Bobrowski <repnop@...gle.com>,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2] sparse: fix incorrect fmode_t casts

The fanotify and open.c changes looks fine, but should be split
into one each with a proper subject and description.

For procfs something simpler like the patch below might be a better
option:

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c1031843cc6aa..c07c6b51f0cb9 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2237,13 +2237,13 @@ static struct dentry *
 proc_map_files_instantiate(struct dentry *dentry,
 			   struct task_struct *task, const void *ptr)
 {
-	fmode_t mode = (fmode_t)(unsigned long)ptr;
+	const fmode_t *mode = ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
 	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK |
-				    ((mode & FMODE_READ ) ? S_IRUSR : 0) |
-				    ((mode & FMODE_WRITE) ? S_IWUSR : 0));
+				    ((*mode & FMODE_READ ) ? S_IRUSR : 0) |
+				    ((*mode & FMODE_WRITE) ? S_IWUSR : 0));
 	if (!inode)
 		return ERR_PTR(-ENOENT);
 
@@ -2294,7 +2294,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 
 	if (vma->vm_file)
 		result = proc_map_files_instantiate(dentry, task,
-				(void *)(unsigned long)vma->vm_file->f_mode);
+				&vma->vm_file->f_mode);
 
 out_no_vma:
 	mmap_read_unlock(mm);
@@ -2391,7 +2391,7 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
 				      buf, len,
 				      proc_map_files_instantiate,
 				      task,
-				      (void *)(unsigned long)p->mode))
+				      &p->mode))
 			break;
 		ctx->pos++;
 	}