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[2a01:c23:b9a1:7300:ace1:b314:fd08:7c6a]) by smtp.googlemail.com with ESMTPSA id 5b1f17b1804b1-41f87d200c6sm111618285e9.23.2024.05.10.15.06.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 May 2024 15:06:05 -0700 (PDT) Message-ID: Date: Sat, 11 May 2024 00:06:04 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: r8169: transmit queue timeouts and IRQ masking To: Ken Milmore , netdev@vger.kernel.org Cc: nic_swsd@realtek.com References: <5181a634-fe25-45e7-803e-eb8737990e01@gmail.com> Content-Language: en-US From: Heiner Kallweit Autocrypt: addr=hkallweit1@gmail.com; keydata= xsFNBF/0ZFUBEAC0eZyktSE7ZNO1SFXL6cQ4i4g6Ah3mOUIXSB4pCY5kQ6OLKHh0FlOD5/5/ sY7IoIouzOjyFdFPnz4Bl3927ClT567hUJJ+SNaFEiJ9vadI6vZm2gcY4ExdIevYHWe1msJF MVE4yNwdS+UsPeCF/6CQQTzHc+n7DomE7fjJD5J1hOJjqz2XWe71fTvYXzxCFLwXXbBiqDC9 dNqOe5odPsa4TsWZ09T33g5n2nzTJs4Zw8fCy8rLqix/raVsqr8fw5qM66MVtdmEljFaJ9N8 /W56qGCp+H8Igk/F7CjlbWXiOlKHA25mPTmbVp7VlFsvsmMokr/imQr+0nXtmvYVaKEUwY2g 86IU6RAOuA8E0J5bD/BeyZdMyVEtX1kT404UJZekFytJZrDZetwxM/cAH+1fMx4z751WJmxQ J7mIXSPuDfeJhRDt9sGM6aRVfXbZt+wBogxyXepmnlv9K4A13z9DVLdKLrYUiu9/5QEl6fgI kPaXlAZmJsQfoKbmPqCHVRYj1lpQtDM/2/BO6gHASflWUHzwmBVZbS/XRs64uJO8CB3+V3fa cIivllReueGCMsHh6/8wgPAyopXOWOxbLsZ291fmZqIR0L5Y6b2HvdFN1Xhc+YrQ8TKK+Z4R mJRDh0wNQ8Gm89g92/YkHji4jIWlp2fwzCcx5+lZCQ1XdqAiHQARAQABzSZIZWluZXIgS2Fs bHdlaXQgPGhrYWxsd2VpdDFAZ21haWwuY29tPsLBjgQTAQgAOBYhBGxfqY/yOyXjyjJehXLe ig9U8DoMBQJf9GRVAhsDBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheAAAoJEHLeig9U8DoMSycQ AJbfg8HZEK0ljV4M8nvdaiNixWAufrcZ+SD8zhbxl8GispK4F3Yo+20Y3UoZ7FcIidJWUUJL axAOkpI/70YNhlqAPMsuudlAieeYZKjIv1WV5ucNZ3VJ7dC+dlVqQdAr1iD869FZXvy91KhJ wYulyCf+s4T9YgmLC6jLMBZghKIf1uhSd0NzjyCqYWbk2ZxByZHgunEShOhHPHswu3Am0ftt ePaYIHgZs+Vzwfjs8I7EuW/5/f5G9w1vibXxtGY/GXwgGGHRDjFM7RSprGOv4F5eMGh+NFUJ TU9N96PQYMwXVxnQfRXl8O6ffSVmFx4H9rovxWPKobLmqQL0WKLLVvA/aOHCcMKgfyKRcLah 57vGC50Ga8oT2K1g0AhKGkyJo7lGXkMu5yEs0m9O+btqAB261/E3DRxfI1P/tvDZpLJKtq35 dXsj6sjvhgX7VxXhY1wE54uqLLHY3UZQlmH3QF5t80MS7/KhxB1pO1Cpcmkt9hgyzH8+5org +9wWxGUtJWNP7CppY+qvv3SZtKJMKsxqk5coBGwNkMms56z4qfJm2PUtJQGjA65XWdzQACib 2iaDQoBqGZfXRdPT0tC1H5kUJuOX4ll1hI/HBMEFCcO8++Bl2wcrUsAxLzGvhINVJX2DAQaF aNetToazkCnzubKfBOyiTqFJ0b63c5dqziAgzsFNBF/0ZFUBEADF8UEZmKDl1w/UxvjeyAeX kghYkY3bkK6gcIYXdLRfJw12GbvMioSguvVzASVHG8h7NbNjk1yur6AONfbUpXKSNZ0skV8V fG+ppbaY+zQofsSMoj5gP0amwbwvPzVqZCYJai81VobefTX2MZM2Mg/ThBVtGyzV3NeCpnBa 8AX3s9rrX2XUoCibYotbbxx9afZYUFyflOc7kEpc9uJXIdaxS2Z6MnYLHsyVjiU6tzKCiVOU KJevqvzPXJmy0xaOVf7mhFSNQyJTrZpLa+tvB1DQRS08CqYtIMxRrVtC0t0LFeQGly6bOngr ircurWJiJKbSXVstLHgWYiq3/GmCSx/82ObeLO3PftklpRj8d+kFbrvrqBgjWtMH4WtK5uN5 1WJ71hWJfNchKRlaJ3GWy8KolCAoGsQMovn/ZEXxrGs1ndafu47yXOpuDAozoHTBGvuSXSZo ythk/0EAuz5IkwkhYBT1MGIAvNSn9ivE5aRnBazugy0rTRkVggHvt3/7flFHlGVGpBHxFUwb /a4UjJBPtIwa4tWR8B1Ma36S8Jk456k2n1id7M0LQ+eqstmp6Y+UB+pt9NX6t0Slw1NCdYTW gJezWTVKF7pmTdXszXGxlc9kTrVUz04PqPjnYbv5UWuDd2eyzGjrrFOsJEi8OK2d2j4FfF++ AzOMdW09JVqejQARAQABwsF2BBgBCAAgFiEEbF+pj/I7JePKMl6Fct6KD1TwOgwFAl/0ZFUC GwwACgkQct6KD1TwOgxUfg//eAoYc0Vm4NrxymfcY30UjHVD0LgSvU8kUmXxil3qhFPS7KA+ y7tgcKLHOkZkXMX5MLFcS9+SmrAjSBBV8omKoHNo+kfFx/dUAtz0lot8wNGmWb+NcHeKM1eb nwUMOEa1uDdfZeKef/U/2uHBceY7Gc6zPZPWgXghEyQMTH2UhLgeam8yglyO+A6RXCh+s6ak Wje7Vo1wGK4eYxp6pwMPJXLMsI0ii/2k3YPEJPv+yJf90MbYyQSbkTwZhrsokjQEaIfjrIk3 rQRjTve/J62WIO28IbY/mENuGgWehRlTAbhC4BLTZ5uYS0YMQCR7v9UGMWdNWXFyrOB6PjSu Trn9MsPoUc8qI72mVpxEXQDLlrd2ijEWm7Nrf52YMD7hL6rXXuis7R6zY8WnnBhW0uCfhajx q+KuARXC0sDLztcjaS3ayXonpoCPZep2Bd5xqE4Ln8/COCslP7E92W1uf1EcdXXIrx1acg21 H/0Z53okMykVs3a8tECPHIxnre2UxKdTbCEkjkR4V6JyplTS47oWMw3zyI7zkaadfzVFBxk2 lo/Tny+FX1Azea3Ce7oOnRUEZtWSsUidtIjmL8YUQFZYm+JUIgfRmSpMFq8JP4VH43GXpB/S OCrl+/xujzvoUBFV/cHKjEQYBxo+MaiQa1U54ykM2W4DnHb1UiEf5xDkFd4= In-Reply-To: <5181a634-fe25-45e7-803e-eb8737990e01@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10.05.2024 00:24, Ken Milmore wrote: > On 08/05/2024 22:14, Heiner Kallweit wrote: >> >> Re-reading &tp->napi may be racy, and I think the code delivers >> a wrong result if NAPI_STATE_SCHEDand NAPI_STATE_DISABLE >> both are set. >> >>> out: >>> rtl_ack_events(tp, status); >> >> The following uses a modified version of napi_schedule_prep() >> to avoid re-reading the napi state. >> We would have to see whether this extension to the net core is >> acceptable, as r8169 would be the only user for now. >> For testing it's one patch, for submitting it would need to be >> splitted. >> >> --- >> drivers/net/ethernet/realtek/r8169_main.c | 6 ++++-- >> include/linux/netdevice.h | 7 ++++++- >> net/core/dev.c | 12 ++++++------ >> 3 files changed, 16 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c >> index eb329f0ab..94b97a16d 100644 >> --- a/drivers/net/ethernet/realtek/r8169_main.c >> +++ b/drivers/net/ethernet/realtek/r8169_main.c >> @@ -4639,6 +4639,7 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance) >> { >> struct rtl8169_private *tp = dev_instance; >> u32 status = rtl_get_events(tp); >> + int ret; >> >> if ((status & 0xffff) == 0xffff || !(status & tp->irq_mask)) >> return IRQ_NONE; >> @@ -4657,10 +4658,11 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance) >> rtl_schedule_task(tp, RTL_FLAG_TASK_RESET_PENDING); >> } >> >> - if (napi_schedule_prep(&tp->napi)) { >> + ret = __napi_schedule_prep(&tp->napi); >> + if (ret >= 0) >> rtl_irq_disable(tp); >> + if (ret > 0) >> __napi_schedule(&tp->napi); >> - } >> out: >> rtl_ack_events(tp, status); >> >> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h >> index 42b9e6dc6..3df560264 100644 >> --- a/include/linux/netdevice.h >> +++ b/include/linux/netdevice.h >> @@ -498,7 +498,12 @@ static inline bool napi_is_scheduled(struct napi_struct *n) >> return test_bit(NAPI_STATE_SCHED, &n->state); >> } >> >> -bool napi_schedule_prep(struct napi_struct *n); >> +int __napi_schedule_prep(struct napi_struct *n); >> + >> +static inline bool napi_schedule_prep(struct napi_struct *n) >> +{ >> + return __napi_schedule_prep(n) > 0; >> +} >> >> /** >> * napi_schedule - schedule NAPI poll >> diff --git a/net/core/dev.c b/net/core/dev.c >> index 4bf081c5a..126eab121 100644 >> --- a/net/core/dev.c >> +++ b/net/core/dev.c >> @@ -6102,21 +6102,21 @@ void __napi_schedule(struct napi_struct *n) >> EXPORT_SYMBOL(__napi_schedule); >> >> /** >> - * napi_schedule_prep - check if napi can be scheduled >> + * __napi_schedule_prep - check if napi can be scheduled >> * @n: napi context >> * >> * Test if NAPI routine is already running, and if not mark >> * it as running. This is used as a condition variable to >> - * insure only one NAPI poll instance runs. We also make >> - * sure there is no pending NAPI disable. >> + * insure only one NAPI poll instance runs. Return -1 if >> + * there is a pending NAPI disable. >> */ >> -bool napi_schedule_prep(struct napi_struct *n) >> +int __napi_schedule_prep(struct napi_struct *n) >> { >> unsigned long new, val = READ_ONCE(n->state); >> >> do { >> if (unlikely(val & NAPIF_STATE_DISABLE)) >> - return false; >> + return -1; >> new = val | NAPIF_STATE_SCHED; >> >> /* Sets STATE_MISSED bit if STATE_SCHED was already set >> @@ -6131,7 +6131,7 @@ bool napi_schedule_prep(struct napi_struct *n) >> >> return !(val & NAPIF_STATE_SCHED); >> } >> -EXPORT_SYMBOL(napi_schedule_prep); >> +EXPORT_SYMBOL(__napi_schedule_prep); >> >> /** >> * __napi_schedule_irqoff - schedule for receive > > Here is a possible alternative (albeit expensive), using a flag in the driver: > > diff --git linux-source-6.1~/drivers/net/ethernet/realtek/r8169_main.c linux-source-6.1/drivers/net/ethernet/realtek/r8169_main.c > index 6e34177..d703af1 100644 > --- linux-source-6.1~/drivers/net/ethernet/realtek/r8169_main.c > +++ linux-source-6.1/drivers/net/ethernet/realtek/r8169_main.c > @@ -579,6 +579,7 @@ enum rtl_flag { > RTL_FLAG_TASK_RESET_PENDING, > RTL_FLAG_TASK_RESET_NO_QUEUE_WAKE, > RTL_FLAG_TASK_TX_TIMEOUT, > + RTL_FLAG_IRQ_DISABLED, > RTL_FLAG_MAX > }; > > @@ -4609,6 +4610,7 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance) > > if (napi_schedule_prep(&tp->napi)) { > rtl_irq_disable(tp); > + set_bit(RTL_FLAG_IRQ_DISABLED, tp->wk.flags); > __napi_schedule(&tp->napi); > } > out: > @@ -4655,12 +4657,17 @@ static int rtl8169_poll(struct napi_struct *napi, int budget) > struct net_device *dev = tp->dev; > int work_done; > > + if (!test_and_set_bit(RTL_FLAG_IRQ_DISABLED, tp->wk.flags)) > + rtl_irq_disable(tp); > + > rtl_tx(dev, tp, budget); > > work_done = rtl_rx(dev, tp, budget); > > - if (work_done < budget && napi_complete_done(napi, work_done)) > + if (work_done < budget && napi_complete_done(napi, work_done)) { > + clear_bit(RTL_FLAG_IRQ_DISABLED, tp->wk.flags); > rtl_irq_enable(tp); > + } > > return work_done; > } > > > > Nice idea. The following is a simplified version. It's based on the thought that between scheduling NAPI and start of NAPI polling interrupts don't hurt. Signed-off-by: Heiner Kallweit --- drivers/net/ethernet/realtek/r8169_main.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c index e5ea827a2..7b04dfecc 100644 --- a/drivers/net/ethernet/realtek/r8169_main.c +++ b/drivers/net/ethernet/realtek/r8169_main.c @@ -592,6 +592,7 @@ enum rtl_flag { RTL_FLAG_TASK_RESET_PENDING, RTL_FLAG_TASK_RESET_NO_QUEUE_WAKE, RTL_FLAG_TASK_TX_TIMEOUT, + RTL_FLAG_IRQ_DISABLED, RTL_FLAG_MAX }; @@ -4657,10 +4658,7 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance) rtl_schedule_task(tp, RTL_FLAG_TASK_RESET_PENDING); } - if (napi_schedule_prep(&tp->napi)) { - rtl_irq_disable(tp); - __napi_schedule(&tp->napi); - } + napi_schedule(&tp->napi); out: rtl_ack_events(tp, status); @@ -4714,12 +4712,17 @@ static int rtl8169_poll(struct napi_struct *napi, int budget) struct net_device *dev = tp->dev; int work_done; + if (!test_and_set_bit(RTL_FLAG_IRQ_DISABLED, tp->wk.flags)) + rtl_irq_disable(tp); + rtl_tx(dev, tp, budget); work_done = rtl_rx(dev, tp, budget); - if (work_done < budget && napi_complete_done(napi, work_done)) + if (work_done < budget && napi_complete_done(napi, work_done)) { + clear_bit(RTL_FLAG_IRQ_DISABLED, tp->wk.flags); rtl_irq_enable(tp); + } return work_done; } -- 2.45.0