From 601e984f23abcaa7cf3eb078c13de4db3cf6a4f0 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Mon, 5 Oct 2020 12:09:11 +0300 Subject: [PATCH 1/2] net: mscc: ocelot: divide watermark value by 60 when writing to SYS_ATOP Tail dropping is enabled for a port when: 1. A source port consumes more packet buffers than the watermark encoded in SYS:PORT:ATOP_CFG.ATOP. AND 2. Total memory use exceeds the consumption watermark encoded in SYS:PAUSE_CFG:ATOP_TOT_CFG. The unit of these watermarks is a 60 byte memory cell. That unit is programmed properly into ATOP_TOT_CFG, but not into ATOP. Actually when written into ATOP, it would get truncated and wrap around. Fixes: a556c76adc05 ("net: mscc: Add initial Ocelot switch support") Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller --- drivers/net/ethernet/mscc/ocelot.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c index 8518e1d60da4f..aa002db04250a 100644 --- a/drivers/net/ethernet/mscc/ocelot.c +++ b/drivers/net/ethernet/mscc/ocelot.c @@ -1253,7 +1253,7 @@ void ocelot_port_set_maxlen(struct ocelot *ocelot, int port, size_t sdu) struct ocelot_port *ocelot_port = ocelot->ports[port]; int maxlen = sdu + ETH_HLEN + ETH_FCS_LEN; int pause_start, pause_stop; - int atop_wm; + int atop, atop_tot; if (port == ocelot->npi) { maxlen += OCELOT_TAG_LEN; @@ -1274,12 +1274,12 @@ void ocelot_port_set_maxlen(struct ocelot *ocelot, int port, size_t sdu) ocelot_fields_write(ocelot, port, SYS_PAUSE_CFG_PAUSE_STOP, pause_stop); - /* Tail dropping watermark */ - atop_wm = (ocelot->shared_queue_sz - 9 * maxlen) / + /* Tail dropping watermarks */ + atop_tot = (ocelot->shared_queue_sz - 9 * maxlen) / OCELOT_BUFFER_CELL_SZ; - ocelot_write_rix(ocelot, ocelot->ops->wm_enc(9 * maxlen), - SYS_ATOP, port); - ocelot_write(ocelot, ocelot->ops->wm_enc(atop_wm), SYS_ATOP_TOT_CFG); + atop = (9 * maxlen) / OCELOT_BUFFER_CELL_SZ; + ocelot_write_rix(ocelot, ocelot->ops->wm_enc(atop), SYS_ATOP, port); + ocelot_write(ocelot, ocelot->ops->wm_enc(atop_tot), SYS_ATOP_TOT_CFG); } EXPORT_SYMBOL(ocelot_port_set_maxlen); From 013264936654fd3052fabe700b7a4933d3925395 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Mon, 5 Oct 2020 12:09:12 +0300 Subject: [PATCH 2/2] net: mscc: ocelot: warn when encoding an out-of-bounds watermark value There is an upper bound to the value that a watermark may hold. That upper bound is not immediately obvious during configuration, and it might be possible to have accidental truncation. Actually this has happened already, add a warning to prevent it from happening again. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller --- drivers/net/dsa/ocelot/felix_vsc9959.c | 2 ++ drivers/net/dsa/ocelot/seville_vsc9953.c | 2 ++ drivers/net/ethernet/mscc/ocelot_vsc7514.c | 2 ++ 3 files changed, 6 insertions(+) diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c index d9c90849274e7..3a9637496407e 100644 --- a/drivers/net/dsa/ocelot/felix_vsc9959.c +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c @@ -1171,6 +1171,8 @@ static int vsc9959_prevalidate_phy_mode(struct ocelot *ocelot, int port, */ static u16 vsc9959_wm_enc(u16 value) { + WARN_ON(value >= 16 * BIT(8)); + if (value >= BIT(8)) return BIT(8) | (value / 16); diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c b/drivers/net/dsa/ocelot/seville_vsc9953.c index 110070a600412..9e9fd19e1d00c 100644 --- a/drivers/net/dsa/ocelot/seville_vsc9953.c +++ b/drivers/net/dsa/ocelot/seville_vsc9953.c @@ -911,6 +911,8 @@ static int vsc9953_prevalidate_phy_mode(struct ocelot *ocelot, int port, */ static u16 vsc9953_wm_enc(u16 value) { + WARN_ON(value >= 16 * BIT(9)); + if (value >= BIT(9)) return BIT(9) | (value / 16); diff --git a/drivers/net/ethernet/mscc/ocelot_vsc7514.c b/drivers/net/ethernet/mscc/ocelot_vsc7514.c index dfb1535f26f29..8a6917691ba68 100644 --- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c +++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c @@ -745,6 +745,8 @@ static int ocelot_reset(struct ocelot *ocelot) */ static u16 ocelot_wm_enc(u16 value) { + WARN_ON(value >= 16 * BIT(8)); + if (value >= BIT(8)) return BIT(8) | (value / 16);