From 323fd785e396f4252b014665df8a831d91c2f117 Mon Sep 17 00:00:00 2001 From: Dean Luick Date: Mon, 16 Nov 2015 21:59:24 -0500 Subject: [PATCH] staging/rdma/hfi1: Fix downgrade race A link downgrade can race with link up. Avoid the race in two ways. First, by having the downgrade application logic take the link state mutex for all of its checking. Second, by waiting for the link to move out of the going up state. Reviewed-by: Dennis Dalessandro Signed-off-by: Dean Luick Signed-off-by: Jubin John Signed-off-by: Greg Kroah-Hartman --- drivers/staging/rdma/hfi1/chip.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/drivers/staging/rdma/hfi1/chip.c b/drivers/staging/rdma/hfi1/chip.c index dc6915947c78..017d439b327a 100644 --- a/drivers/staging/rdma/hfi1/chip.c +++ b/drivers/staging/rdma/hfi1/chip.c @@ -3907,18 +3907,32 @@ void handle_verify_cap(struct work_struct *work) */ void apply_link_downgrade_policy(struct hfi1_pportdata *ppd, int refresh_widths) { - int skip = 1; int do_bounce = 0; - u16 lwde = ppd->link_width_downgrade_enabled; + int tries; + u16 lwde; u16 tx, rx; + /* use the hls lock to avoid a race with actual link up */ + tries = 0; +retry: mutex_lock(&ppd->hls_lock); /* only apply if the link is up */ - if (ppd->host_link_state & HLS_UP) - skip = 0; - mutex_unlock(&ppd->hls_lock); - if (skip) - return; + if (!(ppd->host_link_state & HLS_UP)) { + /* still going up..wait and retry */ + if (ppd->host_link_state & HLS_GOING_UP) { + if (++tries < 1000) { + mutex_unlock(&ppd->hls_lock); + usleep_range(100, 120); /* arbitrary */ + goto retry; + } + dd_dev_err(ppd->dd, + "%s: giving up waiting for link state change\n", + __func__); + } + goto done; + } + + lwde = ppd->link_width_downgrade_enabled; if (refresh_widths) { get_link_widths(ppd->dd, &tx, &rx); @@ -3956,6 +3970,9 @@ void apply_link_downgrade_policy(struct hfi1_pportdata *ppd, int refresh_widths) do_bounce = 1; } +done: + mutex_unlock(&ppd->hls_lock); + if (do_bounce) { set_link_down_reason(ppd, OPA_LINKDOWN_REASON_WIDTH_POLICY, 0, OPA_LINKDOWN_REASON_WIDTH_POLICY); -- 2.20.1