On Sat, Nov 28, 2020 at 05:12:26AM +0000, Al Viro wrote: > On Fri, Nov 20, 2020 at 04:05:47PM -0800, Linus Torvalds wrote: > > On Fri, Nov 20, 2020 at 3:11 PM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > > > > > This set of changes cleanups of the code in exec so hopefully this code > > > will not regress again. Then it adds helpers and fixes the users of > > > files_struct so the reference count is only incremented if COPY_FILES is > > > passed to clone (or if io_uring takes a reference). Then it removes > > > helpers (get_files_struct, __install_fd, __alloc_fd, __close_fd) that > > > are no longer needed and if used would encourage code that increments > > > the count of files_struct somewhere besides in clone when COPY_FILES is > > > passed. > > > > I'm not seeing anything that triggered me going "that looks dodgy". It > > all looks like nice cleanups. > > > > But that's just from reading the patches (and in some cases going and > > looking at the context), so I didn't actually _test_ any of it. It all > > looks sane to me, though, and the fact that it removes a fair number > > of lines of code is always a good sign. > > > > It would be good for people to review and test (Al? Oleg? others?), > > but my gut feel is "this is good". > > Will check (sorry, the last couple of weeks had been bloody awful - > off-net and very short on sleep); I'm digging through the piles of > email right now. TBH, the thing that makes me uneasy about that series is handling the task_lock(). Holding it for longer periods in general, plus boinking it a _lot_ at least on /proc/*/fd getdents(2). There might be other places like that I'd missed - I'm rereading the series now that I've noticed that one. Other than that I mostly like it. I would rather reduce the access to other processes descriptor tables (in particular, slapped a very clear "don't use those helpers unless you really need it; we will be watching for new call sites and you *will* have to explain yourself if you add such" on them), but that's not a new problem - fcheck_files() et.al. had to be watched anyway. One thing I would like to achieve is fewer places grabbing struct file references from descriptor tables other than current->files, but that's mostly orthogonal to this series. I'll need to resurrect a local branch trying to do that; there are conflicts (unsurprisingly), but due to the amount of bitrot it has accumulated it'll have to be redone anyway.
