Re: [PATCH] bpf: convert hashtab lock to raw lock
From: Alexei Starovoitov <hidden>
Date: 2015-10-31 00:04:07
Also in:
linux-rt-users, lkml
On Fri, Oct 30, 2015 at 03:16:26PM -0700, Yang Shi wrote:
When running bpf samples on rt kernel, it reports the below warning: BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917 in_atomic(): 1, irqs_disabled(): 128, pid: 477, name: ping Preemption disabled at:[<ffff80000017db58>] kprobe_perf_func+0x30/0x228
...
quoted hunk ↗ jump to hunk
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 83c209d..972b76b 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c@@ -17,7 +17,7 @@ struct bpf_htab { struct bpf_map map; struct hlist_head *buckets; - spinlock_t lock; + raw_spinlock_t lock;
How do we address such things in general? I bet there are tons of places around the kernel that call spin_lock from atomic. I'd hate to lose the benefits of lockdep of non-raw spin_lock just to make rt happy.