Messages in this thread | | | Date | Fri, 7 Jan 2022 20:04:28 +0800 | Subject | Re: [RFC PATCH net v2 1/2] net/smc: Resolve the race between link group access and termination | From | Wen Gu <> |
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Thanks for your reply.
On 2022/1/7 5:54 pm, Karsten Graul wrote: > On 06/01/2022 14:02, Wen Gu wrote: >> Thanks for your reply. >> >> On 2022/1/5 8:03 pm, Karsten Graul wrote: >>> On 05/01/2022 09:27, Wen Gu wrote: >>>> On 2022/1/3 6:36 pm, Karsten Graul wrote: >>>>> On 31/12/2021 10:44, Wen Gu wrote: >>>>>> On 2021/12/29 8:56 pm, Karsten Graul wrote: >>>>>>> On 28/12/2021 16:13, Wen Gu wrote: >>>>>>>> We encountered some crashes caused by the race between the access >>>>>>>> and the termination of link groups. >> So I am trying this way: >> >> 1) Introduce a new helper smc_conn_lgr_state() to check the three stages mentioned above. >> >> enum smc_conn_lgr_state { >> SMC_CONN_LGR_ORPHAN, /* conn was never registered in a link group */ >> SMC_CONN_LGR_VALID, /* conn is registered in a link group now */ >> SMC_CONN_LGR_INVALID, /* conn was registered in a link group, but now >> is unregistered from it and conn->lgr should >> not be used any more */ >> }; > > Sounds good, but is it really needed to separate 3 cases, i.e. who is really using them 3? > Doesn't it come down to a more simple smc_conn_lgr_valid() which is easier to implement in > the various places in the code? (i.e.: if (smc_conn_lgr_valid()) ....) > Valid would mean conn->lgr != NULL and conn->alert_token_local != 0. The more special cases > would check what they want by there own.
Yes, Most of the time we only need to check whether conn->lgr is in SMC_CONN_LGR_VALID. Only in smc_conn_free() we need to identify whether conn->lgr is in SMC_CONN_LGR_ORPHAN (need a directly return) or SMC_CONN_LGR_INVALID (put link group refcnt and then return).
So I agree with only checking whether conn->lgr is valid with a more simple smc_conn_lgr_valid(). And distinguish SMC_CONN_LGR_ORPHAN and SMC_CONN_LGR_INVALID cases by additional check for conn->lgr.
Thanks, Wen Gu
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