[$] Tracking when BPF programs may sleep

BPF programs can run in both sleepable and non-sleepable (atomic) contexts.Currently, sleepable BPF programs are not allowed to enter an atomic context.Puranjay Mohan has anew patch set that changes that. The patch set would let BPF programs calledin sleepable contexts temporarily acquire locks that cause the programs totransition to an atomic context. BPF maintainer AlexeiStarovoitov objected to parts of the implementation, however, so acceptance ofthe patch depends on whether Mohan is willing and able to straighten it out.