On Fri, 9 Mar 2007, Oliver Neukum wrote: > Am Donnerstag, 8. März 2007 17:02 schrieb Alan Stern: > > On Thu, 8 Mar 2007, Oliver Neukum wrote: > > > > > Hi, > > > > > > after a lightning bolt from high above I've been looking into refcounting > > > the data structures drivers use to provide the data used to refill sysfs > > > buffers. I've come to the following conclusion. > > > > > > 1. struct sysfs_buffer must have a struct kref * and probably a destructor > > > pointer > > > 2. drivers must be able to pass these pointers through an extended > > > device_create_file() > > > 3. Drivers must use refcounting if they want to use attributes > > > 4. read/write/poll must do refcounting > > > > > > I am not sure where to store the pointers. struct sysfs_dirent() looks > > > like the obvious choice. Comments? > > > > Can you explain the reasoning that led to these conclusions? And what > > exactly was your lightning bolt? > > The old race between disconnect and IO to attribute via sysfs again. > If I cannot disassociate the drivers from the buffers in the buffers, drivers > must not deallocate the data necessary to answer sysfs callbacks while > a buffer exists.
Why wouldn't you be able to dissociate a driver from a buffer? That was the whole point of adding .orphan to sysfs_buffer and creating sysfs_buffer_collection -- it was supposed to solve exactly this race. Alan Stern - 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/
