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a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1600098516; bh=X8cS3t6kj/f5e9ta0s+SIetsctK6tG+E1fg6dZnheb4=; h=X-PGP-Universal:ARC-Seal:ARC-Message-Signature: ARC-Authentication-Results:Authentication-Results:Date:From:To:CC: Subject:Message-ID:References:Content-Type:Content-Disposition: In-Reply-To:X-ClientProxiedBy:MIME-Version: X-MS-Exchange-MessageSentRepresentingType:X-Originating-IP: X-MS-PublicTrafficType:X-MS-Office365-Filtering-Correlation-Id: X-MS-TrafficTypeDiagnostic:X-MS-Exchange-Transport-Forked: X-Microsoft-Antispam-PRVS:X-MS-Oob-TLC-OOBClassifiers: X-MS-Exchange-SenderADCheck:X-Microsoft-Antispam: X-Microsoft-Antispam-Message-Info:X-Forefront-Antispam-Report: X-MS-Exchange-AntiSpam-MessageData: X-MS-Exchange-CrossTenant-Network-Message-Id: X-MS-Exchange-CrossTenant-AuthSource: X-MS-Exchange-CrossTenant-AuthAs: X-MS-Exchange-CrossTenant-OriginalArrivalTime: X-MS-Exchange-CrossTenant-FromEntityHeader: X-MS-Exchange-CrossTenant-Id:X-MS-Exchange-CrossTenant-MailboxType: X-MS-Exchange-CrossTenant-UserPrincipalName: X-MS-Exchange-Transport-CrossTenantHeadersStamped:X-OriginatorOrg; b=jf8zhHzbbKl8qflyHTX3ts2P65OQu6C/ovfCjd1SsK2xAMy8t7Y802jqBMiswberu +njClKlmk6o2P0CkmOV0cYhHDuh1t3tbcAPc8WDWQSO+6JtkXdlZNtsXYiqIxJpXGd 5aeGSyEBIKTpPpZLPKUvWaOsyILpfc8pYVFA20ozTS8oCxHVD0ThfXArhn7SFBLv9q 9F1tYR3cRKbdF+xmyF0RCNl714i1+ZLcECbzZ26sUz1IDuEusoEa6zkMcd4k9CHPi7 S1B9ypNs2yZs+DoMNjo+l72J6rgoiVlCd6Mrl46XG8Qs5Ta8jTeQ68QP1g8OrTTzlM UPInHK3TIh3bg== Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Sun, Sep 13, 2020 at 11:02:33AM +0300, Leon Romanovsky wrote: > On Fri, Sep 11, 2020 at 04:52:21PM -0300, Jason Gunthorpe wrote: > > On Thu, Sep 10, 2020 at 05:22:03PM +0300, Leon Romanovsky wrote: > > > From: Avihai Horon > > > > > > Introduce rdma_query_gid_table which enables querying all the GID tables > > > of a given device and copying the attributes of all valid GID entries to > > > a provided buffer. > > > > > > This API provides a faster way to query a GID table using single call and > > > will be used in libibverbs to improve current approach that requires > > > multiple calls to open, close and read multiple sysfs files for a single > > > GID table entry. > > > > > > Signed-off-by: Avihai Horon > > > Signed-off-by: Leon Romanovsky > > > drivers/infiniband/core/cache.c | 93 +++++++++++++++++++++++++ > > > include/rdma/ib_cache.h | 5 ++ > > > include/uapi/rdma/ib_user_ioctl_verbs.h | 8 +++ > > > 3 files changed, 106 insertions(+) > > > > > > diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c > > > index cf49ac0b0aa6..175e229eccd3 100644 > > > +++ b/drivers/infiniband/core/cache.c > > > @@ -1247,6 +1247,99 @@ rdma_get_gid_attr(struct ib_device *device, u8 port_num, int index) > > > } > > > EXPORT_SYMBOL(rdma_get_gid_attr); > > > > > > +/** > > > + * rdma_get_ndev_ifindex - Reads ndev ifindex of the given gid attr. > > > + * @gid_attr: Pointer to the GID attribute. > > > + * @ndev_ifindex: Pointer through which the ndev ifindex is returned. > > > + * > > > + * Returns 0 on success or appropriate error code. The netdevice must be in UP > > > + * state. > > > + */ > > > +int rdma_get_ndev_ifindex(const struct ib_gid_attr *gid_attr, u32 *ndev_ifindex) > > > +{ > > > + struct net_device *ndev; > > > + int ret = 0; > > > + > > > + if (rdma_protocol_ib(gid_attr->device, gid_attr->port_num)) { > > > + *ndev_ifindex = 0; > > > + return 0; > > > + } > > > + > > > + rcu_read_lock(); > > > + ndev = rcu_dereference(gid_attr->ndev); > > > + if (!ndev || (READ_ONCE(ndev->flags) & IFF_UP) == 0) { > > > + ret = -ENODEV; > > > + goto out; > > > + } > > > > None of this is necessary to read the ifindex, especially since the > > read_lock is being held. > > I see same rcu_read_lock->rcu_dereference->rcu_read_unlock pattern in > rdma_read_gid_l2_fields(), why this function is different? It doesn't hold the read_lock so it is using rcu to access attr->ndev. With the read_lock held attr->ndev is stable and none of this is needed. Jason