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Message-ID: <f2244b849e81e26239d232499b1c714b96b2243c.camel@mellanox.com> Date: Wed, 24 Apr 2019 18:43:42 +0000 From: Saeed Mahameed <saeedm@...lanox.com> To: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, Vlad Buslov <vladbu@...lanox.com> CC: "jhs@...atatu.com" <jhs@...atatu.com>, "davem@...emloft.net" <davem@...emloft.net>, "jakub.kicinski@...ronome.com" <jakub.kicinski@...ronome.com>, "xiyou.wangcong@...il.com" <xiyou.wangcong@...il.com>, "jiri@...nulli.us" <jiri@...nulli.us> Subject: Re: [PATCH net-next v2] net: sched: flower: refactor reoffload for concurrent access On Wed, 2019-04-24 at 09:53 +0300, Vlad Buslov wrote: > Recent changes that introduced unlocked flower did not properly > account for > case when reoffload is initiated concurrently with filter updates. To > fix > the issue, extend flower with 'hw_filters' list that is used to store > filters that don't have 'skip_hw' flag set. Filter is added to the > list > when it is inserted to hardware and only removed from it after being > unoffloaded from all drivers that parent block is attached to. This > ensures > that concurrent reoffload can still access filter that is being > deleted and > prevents race condition when driver callback can be removed when > filter is > no longer accessible trough idr, but is still present in hardware. > > Refactor fl_change() to respect new filter reference counter and to > release > filter reference with __fl_put() in case of error, instead of > directly > deallocating filter memory. This allows for concurrent access to > filter > from fl_reoffload() and protects it with reference counting. Refactor > fl_reoffload() to iterate over hw_filters list instead of idr. > Implement > fl_get_next_hw_filter() helper function that is used to iterate over > hw_filters list with reference counting and skips filters that are > being > concurrently deleted. > > Fixes: 92149190067d ("net: sched: flower: set unlocked flag for > flower proto ops") > Signed-off-by: Vlad Buslov <vladbu@...lanox.com> Reviewed-by: Saeed Mahameed <saeedm@...lanox.com> > --- > Changes from V1 to V2: > - Don't verify that list is not empty before calling list_del_init(). > - Assert that rtnl lock is taken in fl_reoffload(). > - Refactor fl_get_next_hw_filter() to simplify the code. > - Remove redundant check for skip_hw flag from fl_reoffload() main > loop. > > net/sched/cls_flower.c | 79 ++++++++++++++++++++++++++++++-------- >
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