[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20250529-stmmac_tstamp_div-v4-1-d73340a794d5@bootlin.com>
Date: Thu, 29 May 2025 11:07:23 +0200
From: Alexis Lothoré <alexis.lothore@...tlin.com>
To: Alexandre Torgue <alexandre.torgue@...s.st.com>,
Jose Abreu <joabreu@...opsys.com>, Andrew Lunn <andrew+netdev@...n.ch>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Richard Cochran <richardcochran@...il.com>,
Phil Reid <preid@...ctromag.com.au>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
Maxime Chevallier <maxime.chevallier@...tlin.com>, netdev@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Jose Abreu <Jose.Abreu@...opsys.com>, Yanteng Si <si.yanteng@...ux.dev>,
Alexis Lothoré <alexis.lothore@...tlin.com>
Subject: [PATCH v4 1/2] net: stmmac: make sure that ptp_rate is not 0
before configuring timestamping
The stmmac platform drivers that do not open-code the clk_ptp_rate value
after having retrieved the default one from the device-tree can end up
with 0 in clk_ptp_rate (as clk_get_rate can return 0). It will
eventually propagate up to PTP initialization when bringing up the
interface, leading to a divide by 0:
Division by zero in kernel.
CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.30-00001-g48313bd5768a #22
Hardware name: STM32 (Device Tree Support)
Call trace:
unwind_backtrace from show_stack+0x18/0x1c
show_stack from dump_stack_lvl+0x6c/0x8c
dump_stack_lvl from Ldiv0_64+0x8/0x18
Ldiv0_64 from stmmac_init_tstamp_counter+0x190/0x1a4
stmmac_init_tstamp_counter from stmmac_hw_setup+0xc1c/0x111c
stmmac_hw_setup from __stmmac_open+0x18c/0x434
__stmmac_open from stmmac_open+0x3c/0xbc
stmmac_open from __dev_open+0xf4/0x1ac
__dev_open from __dev_change_flags+0x1cc/0x224
__dev_change_flags from dev_change_flags+0x24/0x60
dev_change_flags from ip_auto_config+0x2e8/0x11a0
ip_auto_config from do_one_initcall+0x84/0x33c
do_one_initcall from kernel_init_freeable+0x1b8/0x214
kernel_init_freeable from kernel_init+0x24/0x140
kernel_init from ret_from_fork+0x14/0x28
Exception stack(0xe0815fb0 to 0xe0815ff8)
Prevent this division by 0 by adding an explicit check and error log
about the actual issue. While at it, remove the same check from
stmmac_ptp_register, which then becomes duplicate
Fixes: 19d857c9038e ("stmmac: Fix calculations for ptp counters when clock input = 50Mhz.")
Signed-off-by: Alexis Lothoré <alexis.lothore@...tlin.com>
Reviewed-by: Yanteng Si <si.yanteng@...ux.dev>
Reviewed-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
---
Changes in v4:
- collect RB tags
- rebased on net/main
Changes in v3:
- remove now-duplicate check
- reword commit message
---
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 5 +++++
drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c | 2 +-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 085c09039af4a5ebfbb86a3743960d9747367588..1369fa70bc587e5c9e22fc33f69bc9ca0774be86 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -805,6 +805,11 @@ int stmmac_init_tstamp_counter(struct stmmac_priv *priv, u32 systime_flags)
if (!(priv->dma_cap.time_stamp || priv->dma_cap.atime_stamp))
return -EOPNOTSUPP;
+ if (!priv->plat->clk_ptp_rate) {
+ netdev_err(priv->dev, "Invalid PTP clock rate");
+ return -EINVAL;
+ }
+
stmmac_config_hw_tstamping(priv, priv->ptpaddr, systime_flags);
priv->systime_flags = systime_flags;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
index 429b2d357813c8023fc853299f206208f15642e1..3767ba495e78d210b0529ee1754e5331f2dd0a47 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.c
@@ -317,7 +317,7 @@ void stmmac_ptp_register(struct stmmac_priv *priv)
/* Calculate the clock domain crossing (CDC) error if necessary */
priv->plat->cdc_error_adj = 0;
- if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate)
+ if (priv->plat->has_gmac4)
priv->plat->cdc_error_adj = (2 * NSEC_PER_SEC) / priv->plat->clk_ptp_rate;
/* Update the ptp clock parameters based on feature discovery, when
--
2.49.0
Powered by blists - more mailing lists