Messages in this thread | | | From | sainath grandhi <> | Date | Mon, 26 Apr 2021 21:21:04 -0700 | Subject | Question on poll interface in Linux |
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Hello, Looking for some guidance on using poll interfaces in Linux We have a scenario where userspace has to wait on an interrupt from the device. Inclined towards using poll interface on a file descriptor in the userspace. When the device driver executes the interrupt handler, it notifies the file descriptor and wakes up the Userspace thread. Userspace thread reads the interrupt reason and handles the reason.
I am afraid we have a scenario where we could lose notification from kernel to Userspace thread if an interrupt happens during the time window between 2 and 3 steps in the sequence below
1. Userspace thread is woken up 2. Userspace thread read the interrupt reason and handle the interrupt reason 3. Userspace thread goes back to blocked state again for next notification
Brief search on the Linux source code tells me that the kernel notify function will wake up only a sleeping thread. So if the new interrupt happens between steps 2 and 3, and the state of Userspace thread is active, the kernel would not "notify" the Userspace thread and the Userspace processing of new interrupt is missed.
In such scenarios, what is the best kernel-user notification interface to use? Please advise
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