This is a note to let you know that I've just added the patch titled
cifs: do not depend on release_iface for maintaining iface_list
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-do-not-depend-on-release_iface-for-maintaining-iface_list.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 09eeb0723f219fbd96d8865bf9b935e03ee2ec22 Mon Sep 17 00:00:00 2001
From: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
Date: Fri, 29 Dec 2023 11:16:16 +0000
Subject: cifs: do not depend on release_iface for maintaining iface_list
From: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
commit 09eeb0723f219fbd96d8865bf9b935e03ee2ec22 upstream.
parse_server_interfaces should be in complete charge of maintaining
the iface_list linked list. Today, iface entries are removed
from the list only when the last refcount is dropped.
i.e. in release_iface. However, this can result in undercounting
of refcount if the server stops advertising interfaces (which
Azure SMB server does).
This change puts parse_server_interfaces in full charge of
maintaining the iface_list. So if an empty list is returned
by the server, the entries in the list will immediately be
removed. This way, a following call to the same function will
not find entries in the list.
Fixes: aa45dadd34e4 ("cifs: change iface_list from array to sorted linked list")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/smb/client/cifsglob.h | 1 -
fs/smb/client/smb2ops.c | 27 +++++++++++++++++----------
2 files changed, 17 insertions(+), 11 deletions(-)
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -993,7 +993,6 @@ release_iface(struct kref *ref)
struct cifs_server_iface *iface = container_of(ref,
struct cifs_server_iface,
refcount);
- list_del_init(&iface->iface_head);
kfree(iface);
}
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -593,16 +593,12 @@ parse_server_interfaces(struct network_i
}
/*
- * Go through iface_list and do kref_put to remove
- * any unused ifaces. ifaces in use will be removed
- * when the last user calls a kref_put on it
+ * Go through iface_list and mark them as inactive
*/
list_for_each_entry_safe(iface, niface, &ses->iface_list,
- iface_head) {
+ iface_head)
iface->is_active = 0;
- kref_put(&iface->refcount, release_iface);
- ses->iface_count--;
- }
+
spin_unlock(&ses->iface_lock);
/*
@@ -676,10 +672,7 @@ parse_server_interfaces(struct network_i
iface_head) {
ret = iface_cmp(iface, &tmp_iface);
if (!ret) {
- /* just get a ref so that it doesn't get picked/freed */
iface->is_active = 1;
- kref_get(&iface->refcount);
- ses->iface_count++;
spin_unlock(&ses->iface_lock);
goto next_iface;
} else if (ret < 0) {
@@ -746,6 +739,20 @@ next_iface:
}
out:
+ /*
+ * Go through the list again and put the inactive entries
+ */
+ spin_lock(&ses->iface_lock);
+ list_for_each_entry_safe(iface, niface, &ses->iface_list,
+ iface_head) {
+ if (!iface->is_active) {
+ list_del(&iface->iface_head);
+ kref_put(&iface->refcount, release_iface);
+ ses->iface_count--;
+ }
+ }
+ spin_unlock(&ses->iface_lock);
+
return rc;
}
Patches currently in stable-queue which might be from sprasad@xxxxxxxxxxxxx are
queue-6.6/cifs-cifs_chan_is_iface_active-should-be-called-with-chan_lock-held.patch
queue-6.6/cifs-do-not-depend-on-release_iface-for-maintaining-iface_list.patch
