From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:32815) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h2DIh-00030v-E3 for qemu-devel@nongnu.org; Fri, 08 Mar 2019 06:04:28 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h2DIg-0002ze-0t for qemu-devel@nongnu.org; Fri, 08 Mar 2019 06:04:27 -0500 References: <20190308013222.12524-1-philmd@redhat.com> <20190308013222.12524-11-philmd@redhat.com> From: Laszlo Ersek Message-ID: <40a49a86-3010-da90-41f3-0f4a1705bca0@redhat.com> Date: Fri, 8 Mar 2019 12:04:09 +0100 MIME-Version: 1.0 In-Reply-To: <20190308013222.12524-11-philmd@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2 10/18] hw/nvram/fw_cfg: Add reboot_timeout to FWCfgState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Gerd Hoffmann , "Michael S. Tsirkin" , qemu-devel@nongnu.org Cc: Marcel Apfelbaum , Eduardo Habkost , Paolo Bonzini , Richard Henderson , Artyom Tarasenko , "Dr. David Alan Gilbert" , Peter Maydell , David Gibson , Igor Mammedov , Eric Blake , qemu-ppc@nongnu.org, qemu-arm@nongnu.org, Markus Armbruster , Mark Cave-Ayland , Thomas Huth , "Daniel P . Berrange" Hi Phil, On 03/08/19 02:32, Philippe Mathieu-Daud=C3=A9 wrote: > Due to the contract interface of fw_cfg_add_file(), the > 'reboot_timeout' data has to be valid for the lifetime of the > FwCfg object. For this reason it is copied on the heap with > memdup(). >=20 > The object state, 'FWCfgState', is also meant to be valid during the > lifetime of the object. > Move the 'reboot_timeout' in FWCfgState to achieve the same purpose. > Doing so we avoid a memory leak. >=20 > Signed-off-by: Philippe Mathieu-Daud=C3=A9 > --- > hw/nvram/fw_cfg.c | 4 +++- > include/hw/nvram/fw_cfg.h | 2 ++ > 2 files changed, 5 insertions(+), 1 deletion(-) Currently, there is no memory leak. Right now, the leak is theoretical, and it would depend on the fw_cfg object being actually destroyed. I think armoring the fw_cfg implementation for such lifetime actions is valuable. But, that definitely belongs to its own series, in my opinion. In the "hw/nvram/fw_cfg.c" file, I count: (a) two "specific purpose" g_memdup() calls, namely in fw_cfg_bootsplash() and in fw_cfg_reboot(); (b) one "generic purpose" g_memdup() call, namely in fw_cfg_add_string(); (c) two "generic purpose" g_malloc() calls, namely in fw_cfg_add_i16(), fw_cfg_add_i32(), and fw_cfg_add_i64(). (The one in fw_cfg_modify_i16() does not matter here because the previous blob is freed in that function.= ) Your series deals with (a), namely with fw_cfg_reboot() in this patch, and with fw_cfg_bootsplash() in the next one. Your series deals with neither (b) nor (c). The fw_cfg_add_(string|i16|i32|i64) functions are called from a bunch of places however, so if we really intend *not* to leak those copies upon fw_cfg destruction, then we'll have to track all of them dynamically, in a list for example. (And that necessitates a separate series for this topic even more.) In turn, once we add dynamic tracking, for those blobs that the fw_cfg_add_(string|i16|i32|i64) functions allocate internally -- as they are advertized to do --, then we might as well use the same tracking infrastructure for (a). In other words, it should not be necessary to add the specific fields "reboot_timeout" and "boot_splash" to FWCfgState. Thanks, Laszlo >=20 > diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c > index b73a591eff..182d27f59a 100644 > --- a/hw/nvram/fw_cfg.c > +++ b/hw/nvram/fw_cfg.c > @@ -250,7 +250,9 @@ static void fw_cfg_reboot(FWCfgState *s) > } > } > =20 > - fw_cfg_add_file(s, "etc/boot-fail-wait", g_memdup(&rt_val, 4), 4); > + s->reboot_timeout =3D rt_val; > + fw_cfg_add_file(s, "etc/boot-fail-wait", > + &s->reboot_timeout, sizeof(s->reboot_timeout)); > } > =20 > static void fw_cfg_write(FWCfgState *s, uint8_t value) > diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h > index 828ad9dedc..99f6fafcaa 100644 > --- a/include/hw/nvram/fw_cfg.h > +++ b/include/hw/nvram/fw_cfg.h > @@ -53,6 +53,8 @@ struct FWCfgState { > dma_addr_t dma_addr; > AddressSpace *dma_as; > MemoryRegion dma_iomem; > + > + uint32_t reboot_timeout; > }; > =20 > struct FWCfgIoState { >=20