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Date: Mon, 25 Mar 2019 10:23:33 -0600 From: Jens Axboe <axboe@...nel.dk> To: James Bottomley <James.Bottomley@...senPartnership.com>, Arnd Bergmann <arnd@...db.de>, Andrew Morton <akpm@...ux-foundation.org> Cc: Alexander Viro <viro@...iv.linux.org.uk>, Hannes Reinecke <hare@...e.com>, Matthew Wilcox <willy@...radead.org>, David Hildenbrand <david@...hat.com>, Nikolay Borisov <nborisov@...e.com>, linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 1/2] io_uring: fix big-endian compat signal mask handling On 3/25/19 10:19 AM, James Bottomley wrote: > On Mon, 2019-03-25 at 15:34 +0100, Arnd Bergmann wrote: >> On big-endian architectures, the signal masks are differnet >> between 32-bit and 64-bit tasks, so we have to use a different >> function for reading them from user space. >> >> io_cqring_wait() initially got this wrong, and always interprets >> this as a native structure. This is ok on x86 and most arm64, >> but not on s390, ppc64be, mips64be, sparc64 and parisc. >> >> Signed-off-by: Arnd Bergmann <arnd@...db.de> >> --- >> fs/io_uring.c | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index 6aaa30580a2b..8f48d29abf76 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -1968,7 +1968,15 @@ static int io_cqring_wait(struct io_ring_ctx >> *ctx, int min_events, >> return 0; >> >> if (sig) { >> - ret = set_user_sigmask(sig, &ksigmask, &sigsaved, >> sigsz); >> +#ifdef CONFIG_COMPAT >> + if (in_compat_syscall()) >> + ret = set_compat_user_sigmask((const >> compat_sigset_t __user *)sig, >> + &ksigmask, >> &sigsaved, sigsz); >> + else >> +#endif > > This looks a bit suboptimal: shouldn't in_compat_syscall() be hard > coded to return 0 if CONFIG_COMPAT isn't defined? That way the > compiler can do the correct optimization and we don't have to litter > #ifdefs and worry about undefined variables and other things. That requires the types to be valid for !CONFIG_COMPAT, as well as the sigmask helper. -- Jens Axboe
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