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Bruce Allan authored
Based on a patch from Mike McElroy created against the out-of-tree e1000e driver: Hitting the BUG_ON in napi_enable(). Code inspection shows that this can only be triggered by calling napi_enable() twice without an intervening napi_disable(). I saw the following sequence of events in the stack trace: 1) We simulated a cable pull using an Extreme switch. 2) e1000_tx_timeout() was entered. 3) e1000_reset_task() was called. Saw the message from e_err() in the console log. 4) e1000_reinit_locked was called. This function calls e1000_down() and e1000_up(). These functions call napi_disable() and napi_enable() respectively. 5) Then on another thread, a monitor task saw carrier was down and executed 'ip set link down' and 'ip set link up' commands. 6) Saw the '_E1000_RESETTING'warning fron the e1000_close function. 7) Either the e1000_open() executed between the e1000_down() and e1000_up() calls in step 4 or the e1000_open() call executed after the e1000_up() call. In either case, napi_enable() is called twice which triggers the BUG_ON. Signed-off-by:
Bruce Allan <bruce.w.allan@intel.com> Cc: Mike McElroy <mike.mcelroy@stratus.com> Tested-by:
Aaron Brown <aaron.f.brown@intel.com> Signed-off-by:
Jeff Kirsher <jeffrey.t.kirsher@intel.com>
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