On Mon, Oct 22, 2007 at 08:45:39PM -0700, Pete Zaitcev wrote: > On Fri, 19 Oct 2007 20:40:35 +0300, Vitaliy Ivanov <[EMAIL PROTECTED]> wrote: > > Hi, Vitaly, I added you on cc: for the 2.6 cleanup. Please double-check > what I'm doing there and use it for your 2.4 version. I hope my intentions > get clearer with an example. Now, about the specific question: > > > Static lock minor_table_mutex is used for minor table structure. > > And dev->sem for dev manipulations and that's why for open_count. > > If you will simply browse /drivers/usb dir for 2.4 you will see that > > such approach is widely used there. > > What's not right? > > The fundamental reason why you cannot lock a free-able structure with > an in-structure lock is this. Imagine thread A locks in order to process > a disconnect. Thread B wants to open and waits for the lock. Notice that > the struct is not open, so thread A frees it. At this point, thread B > is using a freed memory. > > The solution is to lock the instance struct dev with dev->mtx, except > for the open count, which is locked by a static lock (I'm ignoring > interrupts here, which cannot use mutexes). > > I'm sorry to say, you're quite right: a number of drivers in 2.4 got > it wrong, and some (like adutux) carried it through 2.6.23.
Vitaly, I'm planning on issuing a new 2.4.36 prerelease soon. Have you made any progress on your code after Pete's recommendations ? Thanks, Willy - 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/
