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Alessandro Rubini authored
Unfortunately, we sometimes have threads that block in the I/O operation (the use case is input), and need to be notified when another thread aborts the scheduled operation. This sometimes applies to a user-requested reconfiguration of the trigger. This commit awakes processes sleeping on a cset when the trigger is disabled by a sysfs store, and the chardev interface returns POLLERR in the poll/select functions for control devices. We chose not to affect the data device nor read and write. This means all simple code (scripts, simple demos etc) is not affected. But full-featured applications, which rely on poll, have this additional notification if they check the POLLERR bit. Note: select(2) reports files both readable and writable when the drive returns POLLERR, so applications should really use poll(2) instead. Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
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