Re: [PATCH net 1/6] sctp: remove the unnecessary state check in sctp_outq_tail

quoted

Data Chunks are only sent by sctp_primitive_SEND, in which sctp checks
the asoc's state through statetable before calling sctp_outq_tail. So
there's no need to do it again in sctp_outq_tail.

This patch is to remove it from sctp_outq_tail.

Signed-off-by: Xin Long <lucien.xin@gmail.com>

This doesn't seem safe to me.  The send operation is handled in side effect
processing off a queue that might have operations queued ahead of it, which
affect the associations state.  I think you need to keep this check in place

But not really for Data Chunk.

There are 3 places calling sctp_outq_tail.
1. in sctp_assoc_rwnd_increase():
   it's for sending sack chunk, so this patch is safe for here
2. sctp_cmd_interpreter(), SCTP_CMD_REPLY:
   still not Data Chunk, so safe.
3.SCTP_CMD_SEND_MSG: ->  sctp_cmd_send_msg()
   it's for Data Chunk, but it's only called by sctp_sf_do_prm_send().

#define TYPE_SCTP_PRIMITIVE_SEND  { \
...
/* SCTP_STATE_COOKIE_WAIT */ \
TYPE_SCTP_FUNC(sctp_sf_do_prm_send), \
/* SCTP_STATE_COOKIE_ECHOED */ \
TYPE_SCTP_FUNC(sctp_sf_do_prm_send), \
/* SCTP_STATE_ESTABLISHED */ \
TYPE_SCTP_FUNC(sctp_sf_do_prm_send), \
/* SCTP_STATE_SHUTDOWN_PENDING */ \


in sctp_sf_do_prm_send():
   sctp_add_cmd_sf(commands, SCTP_CMD_SEND_MSG, SCTP_DATAMSG(msg));
   return SCTP_DISPOSITION_CONSUME;

This function is called by PRIMITIVE_SEND, and every time after
calling sctp_do_sm(), there must be no operations inside.
so it's impossible that other operations queued ahead of it.

I'm not sure if I miss some special case, pls correct me if I'm wrong.

Thanks.