| Message ID | 20220606045355.4160711-2-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 35b42dce619701f1300fb8498dae82c9bb1f0263 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: unexport some symbols that are annotated __init | expand |
On 6/6/2022 6:53 AM, Masahiro Yamada wrote: > EXPORT_SYMBOL and __init is a bad combination because the .init.text > section is freed up after the initialization. Hence, modules cannot > use symbols annotated __init. The access to a freed symbol may end up > with kernel panic. > > modpost used to detect it, but it has been broken for a decade. > > Recently, I fixed modpost so it started to warn it again, then this > showed up in linux-next builds. > > There are two ways to fix it: > > - Remove __init > - Remove EXPORT_SYMBOL > > I chose the latter for this case because the only in-tree call-site, > drivers/net/phy/phy_device.c is never compiled as modular. > (CONFIG_PHYLIB is boolean) > > Fixes: 90eff9096c01 ("net: phy: Allow splitting MDIO bus/device support from PHYs") > Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
On Mon, Jun 06, 2022 at 01:53:53PM +0900, Masahiro Yamada wrote: > EXPORT_SYMBOL and __init is a bad combination because the .init.text > section is freed up after the initialization. Hence, modules cannot > use symbols annotated __init. The access to a freed symbol may end up > with kernel panic. > > modpost used to detect it, but it has been broken for a decade. > > Recently, I fixed modpost so it started to warn it again, then this > showed up in linux-next builds. > > There are two ways to fix it: > > - Remove __init > - Remove EXPORT_SYMBOL > > I chose the latter for this case because the only in-tree call-site, > drivers/net/phy/phy_device.c is never compiled as modular. > (CONFIG_PHYLIB is boolean) > > Fixes: 90eff9096c01 ("net: phy: Allow splitting MDIO bus/device support from PHYs") > Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Thanks!
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index 58d602985877..8a2dbe849866 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -1046,7 +1046,6 @@ int __init mdio_bus_init(void) return ret; } -EXPORT_SYMBOL_GPL(mdio_bus_init); #if IS_ENABLED(CONFIG_PHYLIB) void mdio_bus_exit(void)
EXPORT_SYMBOL and __init is a bad combination because the .init.text section is freed up after the initialization. Hence, modules cannot use symbols annotated __init. The access to a freed symbol may end up with kernel panic. modpost used to detect it, but it has been broken for a decade. Recently, I fixed modpost so it started to warn it again, then this showed up in linux-next builds. There are two ways to fix it: - Remove __init - Remove EXPORT_SYMBOL I chose the latter for this case because the only in-tree call-site, drivers/net/phy/phy_device.c is never compiled as modular. (CONFIG_PHYLIB is boolean) Fixes: 90eff9096c01 ("net: phy: Allow splitting MDIO bus/device support from PHYs") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- drivers/net/phy/mdio_bus.c | 1 - 1 file changed, 1 deletion(-)