[Drbd-dev] One more issue with the latest 8.0 tree in git

[Graham, Simon]

Continuing to test the latest 8.0 code from git, I am running into the
following assert a lot:

Jan 29 17:43:50 drbd11: Got NegAck packet. Peer is in troubles?
Jan 29 17:43:50 drbd11: drbd_bm_test_bit: (({ unsigned long flags; do {
(flags) = ((HYPERVISOR_shared_info->vcpu_info +
((current_thread_info()->cpu)))->evtchn_upcall_mask); } while (0);
raw_irqs_disabled_flags(flags); })) in
/sandbox/sgraham/sn/drbd-git/platform/drbd/src/dist/BUILD/drbd-8.0.8/drb
d/drbd_bitmap.c:964
Jan 29 17:43:50  [<c010640a>] show_trace_log_lvl+0x1a/0x30
Jan 29 17:43:50  [<c0106b42>] show_trace+0x12/0x20
Jan 29 17:43:50  [<c0106ba9>] dump_stack+0x19/0x20
Jan 29 17:43:50  [<f152ef34>] drbd_bm_test_bit+0x254/0x260 [drbd]
Jan 29 17:43:50  [<f153e509>] drbd_rs_failed_io+0x1b9/0x3a0 [drbd]
Jan 29 17:43:50  [<f15379c1>] got_NegAck+0x281/0x3a0 [drbd]
Jan 29 17:43:50  [<f15382c8>] drbd_asender+0x2f8/0x5b0 [drbd]
Jan 29 17:43:50  [<f1549a90>] drbd_thread_setup+0xb0/0x170 [drbd]
Jan 29 17:43:50  [<c0103005>] kernel_thread_helper+0x5/0x10
Jan 29 17:43:50  =======================

This is hitting the following test in drbd_bm_test_bit:

	D_BUG_ON(irqs_disabled());
	spin_lock_irq(&b->bm_lock);

I think because this routine is called from places that call
spin_lock_irq() before calling it... Should we just change the
spin_lock_irq() here to spin_lock_irqsave() and remove the D_BUG_ON?

Simon