Prior to commit e6c9a037bc8a ("i2c: xiic: Remove the disabling of
interrupts") IRQs where disabled when the initial __xiic_start_xfer() was
called. After the commit the interrupt is enabled while the function is
running, this means it is possible for the interrupt to be triggered while
the function is still running. When this happens the internal data
structures get corrupted and undefined behavior can occur like the
following crash:
The issue can easily be reproduced by performing I2C access under high
system load or IO load.
To fix the issue protect the invocation to __xiic_start_xfer() form
xiic_start_xfer() with the same lock that is used to protect the interrupt
handler.
Fixes: e6c9a037bc8a ("i2c: xiic: Remove the disabling of interrupts") Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Reviewed-by: Shubhrajyoti Datta <shubhraj@xilinx.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>