Hi Phil, On 03/08/19 02:32, Philippe Mathieu-Daudé 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(). > > 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. > > Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> > --- > 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 > > 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) > } > } > > - fw_cfg_add_file(s, "etc/boot-fail-wait", g_memdup(&rt_val, 4), 4); > + s->reboot_timeout = rt_val; > + fw_cfg_add_file(s, "etc/boot-fail-wait", > + &s->reboot_timeout, sizeof(s->reboot_timeout)); > } > > 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; > }; > > struct FWCfgIoState { >