I'm writing a module that needs to synchronize with its own tasklet (bottom half). Basically, I need to disable the bottom half whenever the driver has been called to do some work. The tasklet is just a periodic timer that keeps the hardware awake, but it should never pre-empty the driver itself. To do this, I have added local_bh_disable() calls at the top of every entry point in my driver. This works very well. However, I would add to like additional checks to make sure that various code is not executed whenever bottom halves are disabled. I discovered function in_softirq(), but I'm having a hard time understanding it. There's no documentation for it (not even any comments!), and the modules in the kernel that do use it don't explain it either. The code for in_softirq() makes me think that it returns non-zero if any thread on this CPU has called local_bh_disable(), which is what I want. But what does in_softirq() means? If I call local_bh_disable(), soft IRQs are disabled, are they not? Isn't that what a bottom-half is, a soft IRQ? - Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/
