Re: [PATCH] remove lots of IS_ERR_VALUE abuses
On Fri, 27 May 2016 23:23:25 +0200 Arnd Bergmann wrote: > Most users of IS_ERR_VALUE() in the kernel are wrong, as they > pass an 'int' into a function that takes an 'unsigned long' > argument. This happens to work because the type is sign-extended > on 64-bit architectures before it gets converted into an > unsigned type. > > However, anything that passes an 'unsigned short' or 'unsigned int' > argument into IS_ERR_VALUE() is guaranteed to be broken, as are > 8-bit integers and types that are wider than 'unsigned long'. > > Andrzej Hajda has already fixed a lot of the worst abusers that > were causing actual bugs, but it would be nice to prevent any > users that are not passing 'unsigned long' arguments. > > This patch changes all users of IS_ERR_VALUE() that I could find > on 32-bit ARM randconfig builds and x86 allmodconfig. For the > moment, this doesn't change the definition of IS_ERR_VALUE() > because there are probably still architecture specific users > elsewhere. So you do plan to add some sort of typechecking into IS_ERR_VALUE()? > Almost all the warnings I got are for files that are better off > using 'if (err)' or 'if (err < 0)'. > The only legitimate user I could find that we get a warning for > is the (32-bit only) freescale fman driver, so I did not remove > the IS_ERR_VALUE() there but changed the type to 'unsigned long'. > For 9pfs, I just worked around one user whose calling conventions > are so obscure that I did not dare change the behavior. > > I was using this definition for testing: > > #define IS_ERR_VALUE(x) ((unsigned long*)NULL == (typeof (x)*)NULL && \ >unlikely((unsigned long long)(x) >= (unsigned long > long)(typeof(x))-MAX_ERRNO)) > > which ends up making all 16-bit or wider types work correctly with > the most plausible interpretation of what IS_ERR_VALUE() was supposed > to return according to its users, but also causes a compile-time > warning for any users that do not pass an 'unsigned long' argument. > > I suggested this approach earlier this year, but back then we ended > up deciding to just fix the users that are obviously broken. After > the initial warning that caused me to get involved in the discussion > (fs/gfs2/dir.c) showed up again in the mainline kernel, Linus > asked me to send the whole thing again. -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] remove lots of IS_ERR_VALUE abuses
On Fri, May 27, 2016 at 2:46 PM, Andrew Morton wrote: > > So you do plan to add some sort of typechecking into IS_ERR_VALUE()? The easiest way to do it is to just turn the (x) into (unsigned long)(void *)(x), which then complains about casting an integer to a pointer if the integer has the wrong size. But if we get rid of the bogus cases, there's just a few left, and we should probably just rename the whole thing (the initial double underscore). It really isn't something normal people should use. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] remove lots of IS_ERR_VALUE abuses
On 27/05/16 22:23, Arnd Bergmann wrote: drivers/acpi/acpi_dbg.c | 22 +++--- drivers/ata/sata_highbank.c | 2 +- drivers/clk/tegra/clk-tegra210.c | 2 +- drivers/cpufreq/omap-cpufreq.c | 2 +- drivers/crypto/caam/ctrl.c | 2 +- drivers/dma/sun4i-dma.c | 16 drivers/gpio/gpio-xlp.c | 2 +- drivers/gpu/drm/sti/sti_vtg.c| 4 ++-- drivers/gpu/drm/tilcdc/tilcdc_tfp410.c | 2 +- drivers/gpu/host1x/hw/intr_hw.c | 2 +- drivers/iommu/arm-smmu-v3.c | 18 +- ... drivers/mmc/host/sdhci-of-at91.c | 2 +- drivers/mmc/host/sdhci.c | 4 ++-- drivers/net/ethernet/freescale/fman/fman.c | 2 +- drivers/net/ethernet/freescale/fman/fman_muram.c | 4 ++-- drivers/net/ethernet/freescale/fman/fman_muram.h | 4 ++-- drivers/net/wireless/ti/wlcore/spi.c | 4 ++-- drivers/nvmem/core.c | 22 +++--- For nvmem part, Acked-by: Srinivas Kandagatla drivers/tty/serial/amba-pl011.c | 2 +- drivers/tty/serial/sprd_serial.c | 2 +- drivers/video/fbdev/da8xx-fb.c | 4 ++-- fs/afs/write.c | 4 fs/binfmt_flat.c | 6 +++--- fs/gfs2/dir.c| 15 +-- kernel/pid.c | 2 +- net/9p/client.c | 4 ++-- sound/soc/qcom/lpass-platform.c | 4 ++-- There is already a patch for this in Mark Brown's sound tree, https://git.kernel.org/cgit/linux/kernel/git/broonie/sound.git/commit/?h=for-linus&id=cef794f76485f4a4e6affd851ae9f9d0eb4287a5 Thanks, srini 38 files changed, 100 insertions(+), 101 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] remove lots of IS_ERR_VALUE abuses
On Fri, May 27, 2016 at 11:23:25PM +0200, Arnd Bergmann wrote:
> @@ -837,7 +837,7 @@ static int load_flat_shared_library(int id, struct
> lib_info *libs)
>
> res = prepare_binprm(&bprm);
>
> - if (!IS_ERR_VALUE(res))
> + if (res >= 0)
if (res == 0), please - prepare_binprm() returns 0 or -E...
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -521,7 +521,7 @@ static int p9_check_errors(struct p9_client *c, struct
> p9_req_t *req)
> if (p9_is_proto_dotu(c))
> err = -ecode;
>
> - if (!err || !IS_ERR_VALUE(err)) {
> + if (!err || !IS_ERR_VALUE((unsigned long)err)) {
Not really - it's actually
if (p9_is_proto_dotu(c) && ecode < 512)
err = -ecode;
if (!err) {
...
> @@ -608,7 +608,7 @@ static int p9_check_zc_errors(struct p9_client *c, struct
> p9_req_t *req,
> if (p9_is_proto_dotu(c))
> err = -ecode;
>
> - if (!err || !IS_ERR_VALUE(err)) {
> + if (!err || !IS_ERR_VALUE((unsigned long)err)) {
Ditto.
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Re: [PATCH] remove lots of IS_ERR_VALUE abuses
On Fri, May 27, 2016 at 2:23 PM, Arnd Bergmann wrote: > > This patch changes all users of IS_ERR_VALUE() that I could find > on 32-bit ARM randconfig builds and x86 allmodconfig. For the > moment, this doesn't change the definition of IS_ERR_VALUE() > because there are probably still architecture specific users > elsewhere. Patch applied with the fixups from Al Viro edited in. I also ended up removing a few other users (due to the vm_brk() interface), and then made IS_ERR_VALUE() do the "void *" cast so that integer use of a non-pointer size should now complain. It works for me and has no new warnings in my allmodconfig build, and with your ARM work that is presumably clean too. But other architectures may see new warnings. People who got affected by this should check their subsystem code for the changes. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
