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i2c: gpio: fault-injector: add 'inject_panic' injector

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Add a fault injector simulating a Kernel panic happening after starting
a transfer. Read the docs for its usage.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Wolfram Sang 2019-02-19 17:39:46 +01:00 committed by Wolfram Sang
parent 63e57b6f19
commit bb6bdd51c8
2 changed files with 56 additions and 1 deletions
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26
Documentation/i2c/gpio-fault-injection
View File

@ -108,3 +108,29 @@ idle bus is:
# echo 200 > lose_arbitration &
# i2cget -y <bus_to_test> 0x3f
Panic during transfer
=====================
This fault injector will create a Kernel panic once the master under test
started a transfer. This usually means that the state machine of the bus master
driver will be ungracefully interrupted and the bus may end up in an unusual
state. Use this to check if your shutdown/reboot/boot code can handle this
scenario.
"inject_panic"
--------------
This file is write only and you need to write the delay between the detected
start of a transmission and the induced Kernel panic (in µs, maximum is 100ms).
The calling process will then sleep and wait for the next bus clock. The
process is interruptible, though.
Start of a transfer is detected by waiting for SCL going down by the master
under test. A good starting point for using this fault injector is:
# echo 0 > inject_panic &
# i2cget -y <bus_to_test> <some_address>
Note that there doesn't need to be a device listening to the address you are
using. Results may vary depending on that, though.

31
drivers/i2c/busses/i2c-gpio.c
View File

@ -231,6 +231,32 @@ static int fops_lose_arbitration_set(void *data, u64 duration)
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");
static irqreturn_t inject_panic_irq(int irq, void *dev_id)
{
struct i2c_gpio_private_data *priv = dev_id;
udelay(priv->scl_irq_data);
panic("I2C fault injector induced panic");
return IRQ_HANDLED;
}
static int fops_inject_panic_set(void *data, u64 duration)
{
struct i2c_gpio_private_data *priv = data;
if (duration > 100 * 1000)
return -EINVAL;
priv->scl_irq_data = duration;
/*
* Interrupt on falling SCL. This ensures that the master under test has
* really started the transfer.
*/
return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
}
DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n");
static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
{
struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
@ -256,9 +282,12 @@ static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
priv, &fops_incomplete_addr_phase);
debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
priv, &fops_incomplete_write_byte);
if (priv->bit_data.getscl)
if (priv->bit_data.getscl) {
debugfs_create_file_unsafe("inject_panic", 0200, priv->debug_dir,
priv, &fops_inject_panic);
debugfs_create_file_unsafe("lose_arbitration", 0200, priv->debug_dir,
priv, &fops_lose_arbitration);
}
debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
}