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rds: don't let RDS shutdown a connection while senders are present

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This is the first in a long line of patches that tries to fix races
between RDS connection shutdown and RDS traffic.

Here we are maintaining a count of active senders to make sure
the connection doesn't go away while they are using it.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2010-05-11 15:11:11 -07:00
committed by Andy Grover
parent 38a4e5e613
commit 7e3f2952ee
5 changed files with 26 additions and 16 deletions
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17
net/rds/send.c
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@@ -60,15 +60,23 @@ void rds_send_reset(struct rds_connection *conn)
struct rds_message *rm, *tmp;
unsigned long flags;
spin_lock_irqsave(&conn->c_send_lock, flags);
if (conn->c_xmit_rm) {
rm = conn->c_xmit_rm;
conn->c_xmit_rm = NULL;
/* Tell the user the RDMA op is no longer mapped by the
* transport. This isn't entirely true (it's flushed out
* independently) but as the connection is down, there's
* no ongoing RDMA to/from that memory */
rds_message_unmapped(conn->c_xmit_rm);
rds_message_put(conn->c_xmit_rm);
conn->c_xmit_rm = NULL;
printk(KERN_CRIT "send reset unmapping %p\n", rm);
rds_message_unmapped(rm);
spin_unlock_irqrestore(&conn->c_send_lock, flags);
rds_message_put(rm);
} else {
spin_unlock_irqrestore(&conn->c_send_lock, flags);
}
conn->c_xmit_sg = 0;
conn->c_xmit_hdr_off = 0;
conn->c_xmit_data_off = 0;
@@ -131,6 +139,7 @@ restart:
ret = -ENOMEM;
goto out;
}
atomic_inc(&conn->c_senders);
if (conn->c_trans->xmit_prepare)
conn->c_trans->xmit_prepare(conn);
@@ -350,6 +359,8 @@ restart:
rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
}
atomic_dec(&conn->c_senders);
/*
* Other senders will see we have c_send_lock and exit. We
* need to recheck the send queue and race again for c_send_lock