| Message ID | 20220506060815.327382-1-francesco.dolcini@toradex.com |
|---|---|
| State | Accepted |
| Commit | 91a7cda1f4b8bdf770000a3b60640576dafe0cec |
| Headers | show |
| Series | [net,v2] net: phy: Fix race condition on link status change | expand |
On Fri, May 06, 2022 at 08:08:15AM +0200, Francesco Dolcini wrote: > 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. > ... > 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@vger.kernel.org> > Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com> whoops, I forgot the changelog, sorry. v2: Added fixes tag, corrected commit message formatting (tab vs space)
Hello, I have one question about the process of patch/fixes backporting to old stable kernel. Assuming the following patch will be deemed correct and applied it will have to be eventually backported. This patch will apply cleanly on v5.15+, but some work is needed to backport to v5.10 or older. Should I send a patch for the older kernels once the fix is merged? Reading Documentation/process/stable-kernel-rules.rst it was not clear to me what to do in this "mixed" situations. Thanks a lot, Francesco On Fri, May 06, 2022 at 08:08:15AM +0200, Francesco Dolcini wrote: > 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@vger.kernel.org> > Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com> > --- > drivers/net/phy/phy.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c > index beb2b66da132..f122026c4682 100644 > --- a/drivers/net/phy/phy.c > +++ b/drivers/net/phy/phy.c > @@ -970,8 +970,13 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat) > { > struct phy_device *phydev = phy_dat; > struct phy_driver *drv = phydev->drv; > + irqreturn_t ret; > > - return drv->handle_interrupt(phydev); > + mutex_lock(&phydev->lock); > + ret = drv->handle_interrupt(phydev); > + mutex_unlock(&phydev->lock); > + > + return ret; > } > > /** > -- > 2.25.1 >
On Fri, May 06, 2022 at 12:10:31PM +0200, Francesco Dolcini wrote: > Hello, > I have one question about the process of patch/fixes backporting > to old stable kernel. > > Assuming the following patch will be deemed correct and applied it will > have to be eventually backported. > > This patch will apply cleanly on v5.15+, but some work is needed to > backport to v5.10 or older. > > Should I send a patch for the older kernels once the fix is merged? > Reading Documentation/process/stable-kernel-rules.rst it was not clear > to me what to do in this "mixed" situations. You will get an email from me if it does not apply to older kernels and you can respond with the backported fix then. thanks, greg k-h
On Fri, May 06, 2022 at 08:08:15AM +0200, Francesco Dolcini wrote: > 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. > > 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@vger.kernel.org> > Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Andrew
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c index beb2b66da132..f122026c4682 100644 --- a/drivers/net/phy/phy.c +++ b/drivers/net/phy/phy.c @@ -970,8 +970,13 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat) { struct phy_device *phydev = phy_dat; struct phy_driver *drv = phydev->drv; + irqreturn_t ret; - return drv->handle_interrupt(phydev); + mutex_lock(&phydev->lock); + ret = drv->handle_interrupt(phydev); + mutex_unlock(&phydev->lock); + + return ret; } /**
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@vger.kernel.org> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com> --- drivers/net/phy/phy.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)