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Date: Sat, 9 May 2020 19:15:23 -0700 From: Shannon Nelson <snelson@...sando.io> To: Andrew Lunn <andrew@...n.ch> Cc: Luis Chamberlain <mcgrof@...nel.org>, jeyu@...nel.org, akpm@...ux-foundation.org, arnd@...db.de, rostedt@...dmis.org, mingo@...hat.com, aquini@...hat.com, cai@....pw, dyoung@...hat.com, bhe@...hat.com, peterz@...radead.org, tglx@...utronix.de, gpiccoli@...onical.com, pmladek@...e.com, tiwai@...e.de, schlad@...e.de, andriy.shevchenko@...ux.intel.com, keescook@...omium.org, daniel.vetter@...ll.ch, will@...nel.org, mchehab+samsung@...nel.org, kvalo@...eaurora.org, davem@...emloft.net, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 00/15] net: taint when the device driver firmware crashes On 5/9/20 6:58 PM, Andrew Lunn wrote: > On Sat, May 09, 2020 at 06:01:51PM -0700, Shannon Nelson wrote: >> On 5/8/20 9:35 PM, Luis Chamberlain wrote: >>> Device driver firmware can crash, and sometimes, this can leave your >>> system in a state which makes the device or subsystem completely >>> useless. Detecting this by inspecting /proc/sys/kernel/tainted instead >>> of scraping some magical words from the kernel log, which is driver >>> specific, is much easier. So instead this series provides a helper which >>> lets drivers annotate this and shows how to use this on networking >>> drivers. >>> >> If the driver is able to detect that the device firmware has come back >> alive, through user intervention or whatever, should there be a way to >> "untaint" the kernel? Or would you expect it to remain tainted? > Hi Shannon > > In general, you don't want to be able to untained. Say a non-GPL > licenced module is loaded, which taints the kernel. It might then try > to untaint the kernel to hide its. Yeah, obviously we don't want this to be abuseable. I was just wondering about reversing this particular status if the broken device could get itself fixed. > > As for firmware, how much damage can the firmware do as it crashed? If > it is a DMA master, it could of splattered stuff through > memory. Restarting the firmware is not going to reverse the damage it > has done. > True, and tho' the driver might get the thing restarted, it wouldn't necessarily know what kind of damage had ensued. Carry on, sln
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