diff mbox series

[net-next,1/4] net: devlink: introduce "unregistering" mark and use it during devlinks iteration

Message ID 20220729071038.983101-2-jiri@resnulli.us (mailing list archive)
State Accepted
Commit c2368b19807affd7621f7c4638cd2e17fec13021
Delegated to: Netdev Maintainers
Headers show
Series net: devlink: allow parallel commands on multiple devlinks | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 2 this patch: 2
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/build_clang success Errors and warnings before: 5 this patch: 5
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 2 this patch: 2
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 34 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Jiri Pirko July 29, 2022, 7:10 a.m. UTC 
From: Jiri Pirko <jiri@nvidia.com>

Add new mark called "unregistering" to be set at the beginning of
devlink_unregister() function. Check this mark during devlinks
iteration in order to prevent getting a reference of devlink which is
being currently unregistered.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
 net/core/devlink.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/net/core/devlink.c b/net/core/devlink.c
index c43c96554a3e..6b20196ada1a 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -207,6 +207,7 @@  static const struct nla_policy devlink_selftest_nl_policy[DEVLINK_ATTR_SELFTEST_
 
 static DEFINE_XARRAY_FLAGS(devlinks, XA_FLAGS_ALLOC);
 #define DEVLINK_REGISTERED XA_MARK_1
+#define DEVLINK_UNREGISTERING XA_MARK_2
 
 /* devlink instances are open to the access from the user space after
  * devlink_register() call. Such logical barrier allows us to have certain
@@ -305,6 +306,14 @@  devlinks_xa_find_get(struct net *net, unsigned long *indexp, xa_mark_t filter,
 	devlink = xa_find_fn(&devlinks, indexp, ULONG_MAX, DEVLINK_REGISTERED);
 	if (!devlink)
 		goto unlock;
+
+	/* In case devlink_unregister() was already called and "unregistering"
+	 * mark was set, do not allow to get a devlink reference here.
+	 * This prevents live-lock of devlink_unregister() wait for completion.
+	 */
+	if (xa_get_mark(&devlinks, *indexp, DEVLINK_UNREGISTERING))
+		goto retry;
+
 	/* For a possible retry, the xa_find_after() should be always used */
 	xa_find_fn = xa_find_after;
 	if (!devlink_try_get(devlink))
@@ -9809,11 +9818,13 @@  void devlink_unregister(struct devlink *devlink)
 	ASSERT_DEVLINK_REGISTERED(devlink);
 	/* Make sure that we are in .remove() routine */
 
+	xa_set_mark(&devlinks, devlink->index, DEVLINK_UNREGISTERING);
 	devlink_put(devlink);
 	wait_for_completion(&devlink->comp);
 
 	devlink_notify_unregister(devlink);
 	xa_clear_mark(&devlinks, devlink->index, DEVLINK_REGISTERED);
+	xa_clear_mark(&devlinks, devlink->index, DEVLINK_UNREGISTERING);
 }
 EXPORT_SYMBOL_GPL(devlink_unregister);