CONFIG_PREEMPT is a preemtion model the so called "Low-Latency Desktop".
A different preemption model is PREEMPT_RT the so called "Real-Time".
Both implement preemption in kernel and set CONFIG_PREEMPTION.
There is also the so called "LAZY PREEMPT" which the "Scheduler
controlled preemption model". Here we have also preemption in the kernel
the rules are slightly different.
Therefore the testsuite should not check for CONFIG_PREEMPT (as one
model) but for CONFIG_PREEMPTION to figure out if preemption in the
kernel is possible.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20241119161819.qvEcs-n_@linutronix.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch adds a test to check for deadlock failure
in bpf_task_storage_{get,delete} when called by a sleepable bpf_lsm prog.
It also checks if the prog_info.recursion_misses is non zero.
The test starts with 32 threads and they are affinitized to one cpu.
In my qemu setup, with CONFIG_PREEMPT=y, I can reproduce it within
one second if it is run without the previous patches of this set.
Here is the test error message before adding the no deadlock detection
version of the bpf_task_storage_{get,delete}:
test_nodeadlock:FAIL:bpf_task_storage_get busy unexpected bpf_task_storage_get busy: actual 2 != expected 0
test_nodeadlock:FAIL:bpf_task_storage_delete busy unexpected bpf_task_storage_delete busy: actual 2 != expected 0
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20221025184524.3526117-9-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Sebastian Andrzej Siewior
Martin KaFai Lau