From 8f3d65c166797746455553f4eaf74a5f89f996d4 Mon Sep 17 00:00:00 2001 From: Karsten Graul Date: Mon, 9 Aug 2021 11:05:56 +0200 Subject: net/smc: fix wait on already cleared link There can be a race between the waiters for a tx work request buffer and the link down processing that finally clears the link. Although all waiters are woken up before the link is cleared there might be waiters which did not yet get back control and are still waiting. This results in an access to a cleared wait queue head. Fix this by introducing atomic reference counting around the wait calls, and wait with the link clear processing until all waiters have finished. Move the work request layer related calls into smc_wr.c and set the link state to INACTIVE before calling smcr_link_clear() in smc_llc_srv_add_link(). Fixes: 15e1b99aadfb ("net/smc: no WR buffer wait for terminating link group") Signed-off-by: Karsten Graul Signed-off-by: Guvenc Gulce Signed-off-by: David S. Miller --- net/smc/smc_tx.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) (limited to 'net/smc/smc_tx.c') diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c index 289025cd545a..c79361dfcdfb 100644 --- a/net/smc/smc_tx.c +++ b/net/smc/smc_tx.c @@ -496,7 +496,7 @@ static int smc_tx_rdma_writes(struct smc_connection *conn, /* Wakeup sndbuf consumers from any context (IRQ or process) * since there is more data to transmit; usable snd_wnd as max transmit */ -static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn) +static int _smcr_tx_sndbuf_nonempty(struct smc_connection *conn) { struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags; struct smc_link *link = conn->lnk; @@ -550,6 +550,22 @@ out_unlock: return rc; } +static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn) +{ + struct smc_link *link = conn->lnk; + int rc = -ENOLINK; + + if (!link) + return rc; + + atomic_inc(&link->wr_tx_refcnt); + if (smc_link_usable(link)) + rc = _smcr_tx_sndbuf_nonempty(conn); + if (atomic_dec_and_test(&link->wr_tx_refcnt)) + wake_up_all(&link->wr_tx_wait); + return rc; +} + static int smcd_tx_sndbuf_nonempty(struct smc_connection *conn) { struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags; -- cgit v1.2.3