On Fri, May 30, 2014 at 1:19 AM, Al Viro <[email protected]> wrote: > On Fri, May 30, 2014 at 12:49:56AM +0200, Kai wrote: >> Hello, >> >> I have recently been playing around with writing a custom filesystem >> for Linux, and have been reading the source of other filesystems, and >> the functions they call into the linux kernel. >> While looking at the function sget in super.c I found something strange. >> >> before if(test) it takes a spinlock, however there seems to be two >> cases where it does not unlock it. >> (Kernel 3.14, super.c line 441) >> >> One: >> if(!grab_super(old)) goto retry; >> Will jump to before spin_lock(), without releasing it first. > > Er... So either grab_super() releases that spinlock, or that thing > is screwed. The next obvious step would be to look into grab_super()... > >> Two: >> And if it finds an old sb, it will return without releasing the lock. > > ... unless something it calls does just that.
AH, I knew I was missing something. And so obvious too =( Thank you for pointing it out to me. Seems I need to spend more time reading the source code and figuring out how it all connects. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
