[PATCH 4.19 5/7] proc: Clear the pieces of proc_inode that proc_evict_inode cares about

[Wen Yang]

From: "Eric W. Biederman" <ebied...@xmission.com>

[ Upstream commit 71448011ea2a1cd36d8f5cbdab0ed716c454d565 ]

This just keeps everything tidier, and allows for using flags like
SLAB_TYPESAFE_BY_RCU where slabs are not always cleared before reuse.
I don't see reuse without reinitializing happening with the proc_inode
but I had a false alarm while reworking flushing of proc dentries and
indoes when a process dies that caused me to tidy this up.

The code is a little easier to follow and reason about this
way so I figured the changes might as well be kept.

Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com>
Cc: <sta...@vger.kernel.org> # 4.19.x
Signed-off-by: Wen Yang <weny...@linux.alibaba.com>
---
 fs/proc/inode.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index fffc7e4..45b4344 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -34,21 +34,27 @@ static void proc_evict_inode(struct inode *inode)
 {
        struct proc_dir_entry *de;
        struct ctl_table_header *head;
+       struct proc_inode *ei = PROC_I(inode);
 
        truncate_inode_pages_final(&inode->i_data);
        clear_inode(inode);
 
        /* Stop tracking associated processes */
-       put_pid(PROC_I(inode)->pid);
+       if (ei->pid) {
+               put_pid(ei->pid);
+               ei->pid = NULL;
+       }
 
        /* Let go of any associated proc directory entry */
-       de = PDE(inode);
-       if (de)
+       de = ei->pde;
+       if (de) {
                pde_put(de);
+               ei->pde = NULL;
+       }
 
-       head = PROC_I(inode)->sysctl;
+       head = ei->sysctl;
        if (head) {
-               RCU_INIT_POINTER(PROC_I(inode)->sysctl, NULL);
+               RCU_INIT_POINTER(ei->sysctl, NULL);
                proc_sys_evict_inode(inode, head);
        }
 }
-- 
1.8.3.1