From: Wen Gu guwen@linux.alibaba.com
commit 56d99e81ecbc997a5f984684d0eeb583992b2072 upstream.
A hung_task is observed when removing SMC-R devices. Suppose that a link group has two active links(lnk_A, lnk_B) associated with two different SMC-R devices(dev_A, dev_B). When dev_A is removed, the link group will be removed from smc_lgr_list and added into lgr_linkdown_list. lnk_A will be cleared and smcibdev(A)->lnk_cnt will reach to zero. However, when dev_B is removed then, the link group can't be found in smc_lgr_list and lnk_B won't be cleared, making smcibdev->lnk_cnt never reaches zero, which causes a hung_task.
This patch fixes this issue by restoring the implementation of smc_smcr_terminate_all() to what it was before commit 349d43127dac ("net/smc: fix kernel panic caused by race of smc_sock"). The original implementation also satisfies the intention that make sure QP destroy earlier than CQ destroy because we will always wait for smcibdev->lnk_cnt reaches zero, which guarantees QP has been destroyed.
Fixes: 349d43127dac ("net/smc: fix kernel panic caused by race of smc_sock") Signed-off-by: Wen Gu guwen@linux.alibaba.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/smc/smc_core.c | 17 +---------------- 1 file changed, 1 insertion(+), 16 deletions(-)
--- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1002,16 +1002,11 @@ void smc_smcd_terminate_all(struct smcd_ /* Called when an SMCR device is removed or the smc module is unloaded. * If smcibdev is given, all SMCR link groups using this device are terminated. * If smcibdev is NULL, all SMCR link groups are terminated. - * - * We must wait here for QPs been destroyed before we destroy the CQs, - * or we won't received any CQEs and cdc_pend_tx_wr cannot reach 0 thus - * smc_sock cannot be released. */ void smc_smcr_terminate_all(struct smc_ib_device *smcibdev) { struct smc_link_group *lgr, *lg; LIST_HEAD(lgr_free_list); - LIST_HEAD(lgr_linkdown_list); int i;
spin_lock_bh(&smc_lgr_list.lock); @@ -1023,7 +1018,7 @@ void smc_smcr_terminate_all(struct smc_i list_for_each_entry_safe(lgr, lg, &smc_lgr_list.list, list) { for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) { if (lgr->lnk[i].smcibdev == smcibdev) - list_move_tail(&lgr->list, &lgr_linkdown_list); + smcr_link_down_cond_sched(&lgr->lnk[i]); } } } @@ -1035,16 +1030,6 @@ void smc_smcr_terminate_all(struct smc_i __smc_lgr_terminate(lgr, false); }
- list_for_each_entry_safe(lgr, lg, &lgr_linkdown_list, list) { - for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) { - if (lgr->lnk[i].smcibdev == smcibdev) { - mutex_lock(&lgr->llc_conf_mutex); - smcr_link_down_cond(&lgr->lnk[i]); - mutex_unlock(&lgr->llc_conf_mutex); - } - } - } - if (smcibdev) { if (atomic_read(&smcibdev->lnk_cnt)) wait_event(smcibdev->lnks_deleted,