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[213.179.129.39]) by smtp.gmail.com with ESMTPSA id 26-20020a170906301a00b006fec56c57f3sm1327952ejz.178.2022.07.29.00.10.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Jul 2022 00:10:40 -0700 (PDT) From: Jiri Pirko To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, idosch@nvidia.com, petrm@nvidia.com, pabeni@redhat.com, edumazet@google.com, mlxsw@nvidia.com, saeedm@nvidia.com, tariqt@nvidia.com, leon@kernel.org, moshe@nvidia.com Subject: [patch net-next 1/4] net: devlink: introduce "unregistering" mark and use it during devlinks iteration Date: Fri, 29 Jul 2022 09:10:35 +0200 Message-Id: <20220729071038.983101-2-jiri@resnulli.us> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220729071038.983101-1-jiri@resnulli.us> References: <20220729071038.983101-1-jiri@resnulli.us> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Jiri Pirko 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 --- net/core/devlink.c | 11 +++++++++++ 1 file changed, 11 insertions(+) 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);