| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <fee98b4f-630e-1685-05e3-e8dae0f412bd@nvidia.com>
Date: Mon, 17 Jun 2019 12:08:06 -0700
From: Bitan Biswas <bbiswas@...dia.com>
To: Dmitry Osipenko <digetx@...il.com>,
Laxman Dewangan <ldewangan@...dia.com>,
Thierry Reding <treding@...dia.com>,
Jonathan Hunter <jonathanh@...dia.com>,
<linux-i2c@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, Peter Rosin <peda@...ntia.se>,
Wolfram Sang <wsa@...-dreams.de>
CC: Shardar Mohammed <smohammed@...dia.com>,
Sowjanya Komatineni <skomatineni@...dia.com>,
Mantravadi Karthik <mkarthik@...dia.com>
Subject: Re: [PATCH V6] i2c: tegra: remove BUG, BUG_ON
On 6/14/19 10:51 AM, Dmitry Osipenko wrote:
> 14.06.2019 18:50, Bitan Biswas пишет:
>> Remove redundant BUG_ON calls or replace with WARN_ON_ONCE
>> as needed. Remove BUG() and mask Rx interrupt similar as Tx
>> for message fully sent case. Add WARN_ON_ONCE check
>> for non-zero rx_fifo_avail in tegra_i2c_empty_rx_fifo()
>> after all processing. Error handling in tegra_i2c_empty_rx_fifo
>> caller is also added.
>>
>> Signed-off-by: Bitan Biswas <bbiswas@...dia.com>
>> ---
>> drivers/i2c/busses/i2c-tegra.c | 46 ++++++++++++++++++++++++++++++++++--------
>> 1 file changed, 38 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
>> index 4dfb4c1..26a7c8c 100644
>> --- a/drivers/i2c/busses/i2c-tegra.c
>> +++ b/drivers/i2c/busses/i2c-tegra.c
>> @@ -73,6 +73,7 @@
>> #define I2C_ERR_NO_ACK BIT(0)
>> #define I2C_ERR_ARBITRATION_LOST BIT(1)
>> #define I2C_ERR_UNKNOWN_INTERRUPT BIT(2)
>> +#define I2C_ERR_UNEXPECTED_STATUS BIT(3)
>
> What about I2C_ERR_RX_BUFFER_OVERFLOW?
OK.
>
>> #define PACKET_HEADER0_HEADER_SIZE_SHIFT 28
>> #define PACKET_HEADER0_PACKET_ID_SHIFT 16
>> @@ -515,15 +516,23 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
>> * prevent overwriting past the end of buf
>> */
>> if (rx_fifo_avail > 0 && buf_remaining > 0) {
>> - BUG_ON(buf_remaining > 3);
>> + /* buf_remaining > 3 check not needed as rx_fifo_avail == 0
>> + * when (words_to_transfer was > rx_fifo_avail) earlier
>> + * in this function
>> + */
>
> Please start all multiline comments with an empty "/*", it should be the correct
> style. There are some places in the kernel where style like yours is used, but I
> assume they are not very correct. Besides, yours variant is not consistent with the
> style of the rest of comments in this source file. And put a dot in the end for
> completeness. Same for the other comments in this patch.
>
OK
>> val = i2c_readl(i2c_dev, I2C_RX_FIFO);
>> val = cpu_to_le32(val);
>> memcpy(buf, &val, buf_remaining);
>> buf_remaining = 0;
>> rx_fifo_avail--;
>> }
>
> Please add a newline here. All logical parts of the code should be separated to ease
> reading and following.
OK
>
>> + if (WARN_ON_ONCE(rx_fifo_avail))
>> + return -EINVAL;
>>
>> - BUG_ON(rx_fifo_avail > 0 && buf_remaining > 0);
>> + /* buf_remaining > 0 at this point can only have rx_fifo_avail == 0
>> + * as this corresponds to (words_to_transfer was > rx_fifo_avail)
>> + * case earlier in this function
>> + */
>> i2c_dev->msg_buf_remaining = buf_remaining;
>> i2c_dev->msg_buf = buf;
>>
>> @@ -581,7 +590,10 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
>> * boundary and fault.
>> */
>> if (tx_fifo_avail > 0 && buf_remaining > 0) {
>> - BUG_ON(buf_remaining > 3);
>> + /* buf_remaining > 3 check not needed as tx_fifo_avail == 0
>> + * when (words_to_transfer was > tx_fifo_avail) earlier
>> + * in this function for non-zero words_to_transfer
>> + */
>> memcpy(&val, buf, buf_remaining);
>> val = le32_to_cpu(val);
>>
>> @@ -811,6 +823,7 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>> u32 status;
>> const u32 status_err = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
>> struct tegra_i2c_dev *i2c_dev = dev_id;
>> + int err_val;
>>
>> status = i2c_readl(i2c_dev, I2C_INT_STATUS);
>>
>> @@ -847,10 +860,21 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>>
>> if (!i2c_dev->is_curr_dma_xfer) {
>> if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
>> - if (i2c_dev->msg_buf_remaining)
>> - tegra_i2c_empty_rx_fifo(i2c_dev);
>> - else
>> - BUG();
>> + err_val = tegra_i2c_empty_rx_fifo(i2c_dev);
>> + if ((!(i2c_dev->msg_buf_remaining)) &&
>
> Let's move this check into tegra_i2c_empty_rx_fifo() and return -EINVAL for that case.
> This will make code to look cleaner.
OK.
>
>> + (!(status & I2C_INT_PACKET_XFER_COMPLETE)) &&
>
> It shouldn't matter that XFER_COMPLETE is set if RX FIFO isn't fully emptied because
> it always shall be emptied. Hence this check is not needed and we should error out
> regardless.
OK
>
>> + err_val) {
>> + /*
>> + * Overflow error condition: message fully sent,
>> + * with no XFER_COMPLETE interrupt but hardware
>> + * asks to transfer more.
>> + */
>> + tegra_i2c_mask_irq(i2c_dev,
>> + I2C_INT_RX_FIFO_DATA_REQ);
>
> No need to mask RX_FIFO_DATA_REQ here because all interrupts are masked on "goto
> err:", hence just remove the tegra_i2c_mask_irq().
>
>> + i2c_dev->msg_err |=
>> + I2C_ERR_UNEXPECTED_STATUS;
>
> No need to split this into two lines because it's less than 80 chars, write this in a
> single line.
OK
>
>> + goto err;
>> + }
>> }
>>
>> if (!i2c_dev->msg_read && (status & I2C_INT_TX_FIFO_DATA_REQ)) {
>> @@ -876,7 +900,13 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>> if (status & I2C_INT_PACKET_XFER_COMPLETE) {
>> if (i2c_dev->is_curr_dma_xfer)
>> i2c_dev->msg_buf_remaining = 0;
>> - BUG_ON(i2c_dev->msg_buf_remaining);
>> + /* Underflow error condition: XFER_COMPLETE before message
>> + * fully sent.
>> + */
>> + if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining)) {
>> + i2c_dev->msg_err |= I2C_ERR_UNKNOWN_INTERRUPT;
>> + goto err;
>> + }
>> complete(&i2c_dev->msg_complete);
>> }
>> goto done;
>>
>
> Please address comments in the next revision.
>
Sorry for the delayed reply. I shared Patch V7 with above changes
earlier today.
-regards,
Bitan
Powered by blists - more mailing lists