On Wed, 19 Aug 2020 10:29:09 -0700 Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx> wrote: > What I don't understand in the stack trace is this: > > > [ 107.654661] Call Trace: > > > [ 107.657735] <IRQ> > > > [ 107.663155] ? ftrace_graph_caller+0xc0/0xc0 > > > [ 107.667929] call_timer_fn+0x3b/0x1b0 > > > [ 107.672238] ? netif_carrier_off+0x70/0x70 > > > [ 107.677771] ? netif_carrier_off+0x70/0x70 > > > [ 107.682656] ? ftrace_graph_caller+0xc0/0xc0 > > > [ 107.687379] run_timer_softirq+0x3e8/0xa10 > > > [ 107.694653] ? call_timer_fn+0x1b0/0x1b0 > > > [ 107.699382] ? trace_event_raw_event_softirq+0xdd/0x150 > > > [ 107.706768] ? ring_buffer_unlock_commit+0xf5/0x210 > > > [ 107.712213] ? call_timer_fn+0x1b0/0x1b0 > > > [ 107.716625] ? __do_softirq+0x155/0x467 > > > If the carrier was turned off by something, that could cause the stack > to timeout since it appears the driver didn't call this itself after > finishing all transmits like it normally would have. > > Is the trace above correct? Usually the ? indicate unsure backtrace due > to missing symbols, right? The "?" means that there wasn't a stack frame to confirm that this was the true call stack. What happens is that the scan of the stack will look for any address in the stack that is for a function. If it finds one, it will print it and add a "?" to that address. Basically, those functions with the "?" are just addresses found in the stack but was not part of a stack frame link. -- Steve
