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net: devlink: introduce "unregistering" mark and use it during devlinks iteration

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Pirko 2022-07-29 09:10:35 +02:00 committed by David S. Miller
parent 02a7cb2866
commit c2368b1980
1 changed files with 11 additions and 0 deletions
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11
net/core/devlink.c
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@ -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 @@ retry:
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);