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Typically, when the CM sends a MAD it bumps a reference count on the associated cm_id. There are some exceptions, such as when the MAD is a direct response to a receive MAD. For example, the CM may generate an MRA in response to a duplicate REQ. But, in general, if a MAD may be sent as a result of the user invoking an API call (e.g. ib_send_cm_rep(), ib_send_cm_rtu(), etc.), a reference is taken on the cm_id. This reference is necessary if the MAD requires a response. The reference allows routing a response MAD back to the cm_id, or, if no response is received, allows updating the cm_id state to reflect the failure. For MADs which do not generate a response from the target, however, there's no need to hold a reference on the cm_id. Such MADs will not be retried by the MAD layer and their completions do not change the state of the cm_id. There are 2 internal calls used to allocate MADs which take a reference on the cm_id: cm_alloc_msg() and cm_alloc_priv_msg(). The latter calls the former. It turns out that all other places where cm_alloc_msg() is called are for MADs that do not generate a response from the target: sending an RTU, DREP, REJ, MRA, or SIDR REP. In all of these cases, there's no need to hold a reference on the cm_id. The benefit of dropping unneeded references is that it allows destruction of the cm_id to proceed immediately. Currently, the cm_destroy_id() call blocks as long as there's a reference held on the cm_id. Worse, is that cm_destroy_id() will send MADs, which it then needs to complete. Sending the MADs is beneficial, as they notify the peer that a connection is being destroyed. However, since the MADs hold a reference on the cm_id, they block destruction and cannot be retried. Move cm_id referencing from cm_alloc_msg() to cm_alloc_priv_msg(). The latter should hold a reference on the cm_id in all cases but one, which will be handled in a separate patch. cm_alloc_priv_msg() is used when sending a REQ, REP, DREQ, and SIDR REQ, all of which require a response. Also, merge common code into cm_alloc_priv_msg() and combine the freeing of all messages which do not need a response. Signed-off-by: Sean Hefty <shefty@nvidia.com> Signed-off-by: Or Har-Toov <ohartoov@nvidia.com> Signed-off-by: Vlad Dumitrescu <vdumitrescu@nvidia.com> Link: https://patch.msgid.link/1f0f96acace72790ecf89087fc765dead960189e.1731495873.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org> |
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