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Message-Id: <20220516193615.903600331@linuxfoundation.org>
Date: Mon, 16 May 2022 21:36:51 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Francesco Dolcini <francesco.dolcini@...adex.com>,
Andrew Lunn <andrew@...n.ch>, Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH 5.4 40/43] net: phy: Fix race condition on link status change
From: Francesco Dolcini <francesco.dolcini@...adex.com>
commit 91a7cda1f4b8bdf770000a3b60640576dafe0cec upstream.
This fixes the following error caused by a race condition between
phydev->adjust_link() and a MDIO transaction in the phy interrupt
handler. The issue was reproduced with the ethernet FEC driver and a
micrel KSZ9031 phy.
[ 146.195696] fec 2188000.ethernet eth0: MDIO read timeout
[ 146.201779] ------------[ cut here ]------------
[ 146.206671] WARNING: CPU: 0 PID: 571 at drivers/net/phy/phy.c:942 phy_error+0x24/0x6c
[ 146.214744] Modules linked in: bnep imx_vdoa imx_sdma evbug
[ 146.220640] CPU: 0 PID: 571 Comm: irq/128-2188000 Not tainted 5.18.0-rc3-00080-gd569e86915b7 #9
[ 146.229563] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 146.236257] unwind_backtrace from show_stack+0x10/0x14
[ 146.241640] show_stack from dump_stack_lvl+0x58/0x70
[ 146.246841] dump_stack_lvl from __warn+0xb4/0x24c
[ 146.251772] __warn from warn_slowpath_fmt+0x5c/0xd4
[ 146.256873] warn_slowpath_fmt from phy_error+0x24/0x6c
[ 146.262249] phy_error from kszphy_handle_interrupt+0x40/0x48
[ 146.268159] kszphy_handle_interrupt from irq_thread_fn+0x1c/0x78
[ 146.274417] irq_thread_fn from irq_thread+0xf0/0x1dc
[ 146.279605] irq_thread from kthread+0xe4/0x104
[ 146.284267] kthread from ret_from_fork+0x14/0x28
[ 146.289164] Exception stack(0xe6fa1fb0 to 0xe6fa1ff8)
[ 146.294448] 1fa0: 00000000 00000000 00000000 00000000
[ 146.302842] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 146.311281] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 146.318262] irq event stamp: 12325
[ 146.321780] hardirqs last enabled at (12333): [<c01984c4>] __up_console_sem+0x50/0x60
[ 146.330013] hardirqs last disabled at (12342): [<c01984b0>] __up_console_sem+0x3c/0x60
[ 146.338259] softirqs last enabled at (12324): [<c01017f0>] __do_softirq+0x2c0/0x624
[ 146.346311] softirqs last disabled at (12319): [<c01300ac>] __irq_exit_rcu+0x138/0x178
[ 146.354447] ---[ end trace 0000000000000000 ]---
With the FEC driver phydev->adjust_link() calls fec_enet_adjust_link()
calls fec_stop()/fec_restart() and both these function reset and
temporary disable the FEC disrupting any MII transaction that
could be happening at the same time.
fec_enet_adjust_link() and phy_read() can be running at the same time
when we have one additional interrupt before the phy_state_machine() is
able to terminate.
Thread 1 (phylib WQ) | Thread 2 (phy interrupt)
|
| phy_interrupt() <-- PHY IRQ
| handle_interrupt()
| phy_read()
| phy_trigger_machine()
| --> schedule phylib WQ
|
|
phy_state_machine() |
phy_check_link_status() |
phy_link_change() |
phydev->adjust_link() |
fec_enet_adjust_link() |
--> FEC reset | phy_interrupt() <-- PHY IRQ
| phy_read()
|
Fix this by acquiring the phydev lock in phy_interrupt().
Link: https://lore.kernel.org/all/20220422152612.GA510015@francesco-nb.int.toradex.com/
Fixes: c974bdbc3e77 ("net: phy: Use threaded IRQ, to allow IRQ from sleeping devices")
cc: <stable@...r.kernel.org>
Signed-off-by: Francesco Dolcini <francesco.dolcini@...adex.com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Link: https://lore.kernel.org/r/20220506060815.327382-1-francesco.dolcini@toradex.com
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
[fd: backport: adapt locking before did_interrupt()/ack_interrupt()
callbacks removal ]
Signed-off-by: Francesco Dolcini <francesco.dolcini@...adex.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/net/phy/phy.c | 45 ++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 40 insertions(+), 5 deletions(-)
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -116,10 +116,15 @@ EXPORT_SYMBOL(phy_print_status);
*/
static int phy_clear_interrupt(struct phy_device *phydev)
{
- if (phydev->drv->ack_interrupt)
- return phydev->drv->ack_interrupt(phydev);
+ int ret = 0;
- return 0;
+ if (phydev->drv->ack_interrupt) {
+ mutex_lock(&phydev->lock);
+ ret = phydev->drv->ack_interrupt(phydev);
+ mutex_unlock(&phydev->lock);
+ }
+
+ return ret;
}
/**
@@ -761,6 +766,36 @@ static int phy_disable_interrupts(struct
}
/**
+ * phy_did_interrupt - Checks if the PHY generated an interrupt
+ * @phydev: target phy_device struct
+ */
+static int phy_did_interrupt(struct phy_device *phydev)
+{
+ int ret;
+
+ mutex_lock(&phydev->lock);
+ ret = phydev->drv->did_interrupt(phydev);
+ mutex_unlock(&phydev->lock);
+
+ return ret;
+}
+
+/**
+ * phy_handle_interrupt - PHY specific interrupt handler
+ * @phydev: target phy_device struct
+ */
+static int phy_handle_interrupt(struct phy_device *phydev)
+{
+ int ret;
+
+ mutex_lock(&phydev->lock);
+ ret = phydev->drv->handle_interrupt(phydev);
+ mutex_unlock(&phydev->lock);
+
+ return ret;
+}
+
+/**
* phy_interrupt - PHY interrupt handler
* @irq: interrupt line
* @phy_dat: phy_device pointer
@@ -771,11 +806,11 @@ static irqreturn_t phy_interrupt(int irq
{
struct phy_device *phydev = phy_dat;
- if (phydev->drv->did_interrupt && !phydev->drv->did_interrupt(phydev))
+ if (phydev->drv->did_interrupt && !phy_did_interrupt(phydev))
return IRQ_NONE;
if (phydev->drv->handle_interrupt) {
- if (phydev->drv->handle_interrupt(phydev))
+ if (phy_handle_interrupt(phydev))
goto phy_err;
} else {
/* reschedule state queue work to run as soon as possible */
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