working my way through work queues and read this in workqueue.h:
/**
* flush_scheduled_work - ensure that any scheduled work has run to completion.
*
* Forces execution of the kernel-global workqueue and blocks until its
* completion.
*
* Think twice before calling this function! It's very easy to get into
* trouble if you don't take great care. Either of the following situations
* will lead to deadlock:
*
* One of the work items currently on the workqueue needs to acquire
* a lock held by your code or its caller.
*
* Your code is running in the context of a work routine.
*
* They will be detected by lockdep when they occur, but the first might not
* occur very often. It depends on what work items are on the workqueue and
* what locks they need, which you have no control over.
*
* In most situations flushing the entire workqueue is overkill; you merely
* need to know that a particular work item isn't queued and isn't running.
* In such cases you should use cancel_delayed_work_sync() or
* cancel_work_sync() instead.
*/
and yet, there are quite a few drivers that do just that:
$ grep -rw flush_scheduled_work drivers
drivers/scsi/scsi_scan.c: flush_scheduled_work();
drivers/scsi/qla2xxx/qla_target.c: flush_scheduled_work();
drivers/leds/leds-blinkm.c: flush_scheduled_work();
drivers/acpi/osl.c: * which invoke flush_scheduled_work/acpi_os_wait_events_complete
drivers/staging/olpc_dcon/olpc_dcon.c: flush_scheduled_work();
drivers/staging/rtl8192u/r8192U_core.c:// flush_scheduled_work();
drivers/staging/wlan-ng/prism2usb.c: flush_scheduled_work();
drivers/staging/iio/light/tsl2563.c: flush_scheduled_work();
drivers/staging/iio/light/tsl2563.c: flush_scheduled_work();
drivers/staging/rtl8712/usb_intf.c: flush_scheduled_work();
drivers/message/fusion/mptscsih.c: flush_scheduled_work();
drivers/rtc/rtc-dev.c: flush_scheduled_work();
drivers/rtc/rtc-88pm860x.c: flush_scheduled_work();
drivers/misc/mei/main.c: flush_scheduled_work();
drivers/misc/mei/main.c: flush_scheduled_work();
... snip, even more after this ...
so what's up with that? it seems inconsistent to describe that
kernel-wide routine as "overkill" while a number of drivers continue
to use it.
rday
--
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Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca
Twitter: http://twitter.com/rpjday
LinkedIn: http://ca.linkedin.com/in/rpjday
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