Messages in this thread |  | | Subject | Re: [PATCH 3/9] nvme: change namespaces_mutext to namespaces_rwsem | From | "jianchao.wang" <> | Date | Mon, 12 Feb 2018 10:33:37 +0800 |
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Hi Sagi
Thanks for your kindly response. And sorry for my bad description.
On 02/11/2018 07:17 PM, Sagi Grimberg wrote: >> namespaces_mutext is used to synchronize the operations on ctrl >> namespaces list. Most of the time, it is a read operation. It is >> better to change it from mutex to rwsem. >> >> On the other hand, the namespaces mutex could introduce circular >> dependency easily. > > On the other hand of what? > > Also, can you give an example of such? >
We have a lot of interface in nvme core that need to hold this namespace_mutex and looks like we will have more. The mutex will trouble us in following scenario.
For example:
context A context B nvme_xxx_xxx nvme_xxx_xxx -> hold namespace_mutex -> try to require namespace_mutex -> sync context B
Keith's patch will incur this. http://lists.infradead.org/pipermail/linux-nvme/2018-February/015605.html
Because I add a interface that will hold namespace_mutex, so I add this patchset here.
Thanks Jianchao > _______________________________________________ > Linux-nvme mailing list > Linux-nvme@lists.infradead.org > https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_mailman_listinfo_linux-2Dnvme&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=7WdAxUBeiTUTCy8v-7zXyr4qk7sx26ATvfo6QSTvZyQ&m=7MZaKEgFTQoH0JODWrGtapw7rGRwXzyRBi-OKlhNaTE&s=-L_YlxhBS6aEW6Gt5tI4bV67eWn4JdvW2Nh3HAZ111Y&e= >
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