On Fri, Oct 11, 2019 at 11:36:33AM +0200, Johan Hovold wrote: > On Thu, Oct 10, 2019 at 03:50:43PM +0200, Daniel Vetter wrote: > > On Thu, Oct 10, 2019 at 03:13:29PM +0200, Johan Hovold wrote: > > > Two old USB drivers had a bug in them which could lead to memory leaks > > > if an interrupted process raced with a disconnect event. > > > > > > Turns out we had a few more driver in other subsystems with the same > > > kind of bug in them. > > > Random funny idea: Could we do some debug annotations (akin to > > might_sleep) that splats when you might_sleep_interruptible somewhere > > where interruptible sleeps are generally a bad idea? Like in > > fops->release? > > There's nothing wrong with interruptible sleep in fops->release per se, > it's just that drivers cannot return -ERESTARTSYS and friends and expect > to be called again later. Do you have a legit usecase for interruptible sleeps in fops->release? I'm not even sure killable is legit in there, since it's an fd, not a process context ... > The return value from release() is ignored by vfs, and adding a splat in > __fput() to catch these buggy drivers might be overkill. Ime once you have a handful of instances of a broken pattern, creating a check for it (under a debug option only ofc) is very much justified. Otherwise they just come back to life like the undead, all the time. And there's a _lot_ of fops->release callbacks in the kernel. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
