From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:54120) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gr10t-0007z3-La for qemu-devel@nongnu.org; Tue, 05 Feb 2019 08:43:48 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gr10r-0006RE-Tr for qemu-devel@nongnu.org; Tue, 05 Feb 2019 08:43:47 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:43250) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gr10p-0006Nm-PD for qemu-devel@nongnu.org; Tue, 05 Feb 2019 08:43:44 -0500 Received: by mail-wr1-f67.google.com with SMTP id r2so3636181wrv.10 for ; Tue, 05 Feb 2019 05:43:42 -0800 (PST) References: <20190129175403.18017-1-philmd@redhat.com> <20190129175403.18017-14-philmd@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: <09d73785-35b9-ab39-b40d-1753537ba99d@redhat.com> Date: Tue, 5 Feb 2019 14:43:39 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC PATCH v2 13/18] oslib-posix: Ignore fcntl("/dev/null", F_SETFL, O_NONBLOCK) failure List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Brad Smith , QEMU Developers , Stefan Hajnoczi , Qemu-block , Igor Mammedov , Paolo Bonzini , Eric Blake , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Kevin Wolf , Max Reitz , Markus Armbruster , Fam Zheng , "Michael S. Tsirkin" , Kamil Rytarowski On 2/5/19 2:22 PM, Peter Maydell wrote: > On Tue, 29 Jan 2019 at 17:59, Philippe Mathieu-Daudé wrote: >> >> Previous to OpenBSD 6.3 [1], fcntl(F_SETFL) is not permitted on >> memory devices. >> Trying this call sets errno to ENODEV ("not a memory device"): >> >> 19 ENODEV Operation not supported by device. >> An attempt was made to apply an inappropriate function to a device, >> for example, trying to read a write-only device such as a printer. >> >> Do not assert fcntl failures in this specific case (errno set to ENODEV) >> on OpenBSD. This fixes: >> >> $ lm32-softmmu/qemu-system-lm32 >> assertion "f != -1" failed: file "util/oslib-posix.c", line 247, function "qemu_set_nonblock" >> Abort trap (core dumped) >> >> [1] The fix seems https://github.com/openbsd/src/commit/c2a35b387f9d3c >> "fcntl(F_SETFL) invokes the FIONBIO and FIOASYNC ioctls internally, so >> the memory devices (/dev/null, /dev/zero, etc) need to permit them." >> >> Signed-off-by: Philippe Mathieu-Daudé >> --- >> util/oslib-posix.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/util/oslib-posix.c b/util/oslib-posix.c >> index 4ce1ba9ca4..2f0f27e6d9 100644 >> --- a/util/oslib-posix.c >> +++ b/util/oslib-posix.c >> @@ -244,7 +244,17 @@ void qemu_set_nonblock(int fd) >> f = fcntl(fd, F_GETFL); >> assert(f != -1); >> f = fcntl(fd, F_SETFL, f | O_NONBLOCK); >> +#ifdef __OpenBSD__ >> + if (f == -1) { >> + /* >> + * Previous to OpenBSD 6.3, fcntl(F_SETFL) is not permitted on >> + * memory devices and sets errno to ENODEV. >> + */ >> + assert(errno == ENODEV); >> + } >> +#else >> assert(f != -1); >> +#endif > > You might also add "It's OK if we fail to set O_NONBLOCK on devices > like /dev/null, because they will never block anyway." OK! > Reviewed-by: Peter Maydell Thanks for reviewing this series :) > > thanks > -- PMM >