remove lots of IS_ERR_VALUE abuses

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.

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.

[ Updated the 9p parts as per Al Viro  - Linus ]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.org/lkml/2016/1/7/363
Link: https://lkml.org/lkml/2016/5/27/486
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> # For nvmem part
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 9 insertions, 9 deletions

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index b81b08f81325..c984321d1881 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1276,7 +1276,7 @@ static int mmc_select_hs200(struct mmc_card *card)
 	 * switch to HS200 mode if bus width is set successfully.
 	 */
 	err = mmc_select_bus_width(card);
-	if (!IS_ERR_VALUE(err)) {
+	if (!err) {
 		val = EXT_CSD_TIMING_HS200 |
 		      card->drive_strength << EXT_CSD_DRV_STR_SHIFT;
 		err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
@@ -1583,7 +1583,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 	} else if (mmc_card_hs(card)) {
 		/* Select the desired bus width optionally */
 		err = mmc_select_bus_width(card);
-		if (!IS_ERR_VALUE(err)) {
+		if (!err) {
 			err = mmc_select_hs_ddr(card);
 			if (err)
 				goto free_card;
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 829a6eebcdce..2cc6123b1df9 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1431,7 +1431,7 @@ static int dw_mci_get_ro(struct mmc_host *mmc)
 	int gpio_ro = mmc_gpio_get_ro(mmc);
 
 	/* Use platform get_ro function, else try on board write protect */
-	if (!IS_ERR_VALUE(gpio_ro))
+	if (gpio_ro >= 0)
 		read_only = gpio_ro;
 	else
 		read_only =
@@ -1454,7 +1454,7 @@ static int dw_mci_get_cd(struct mmc_host *mmc)
 	if ((mmc->caps & MMC_CAP_NEEDS_POLL) ||
 	    (mmc->caps & MMC_CAP_NONREMOVABLE))
 		present = 1;
-	else if (!IS_ERR_VALUE(gpio_cd))
+	else if (gpio_cd >= 0)
 		present = gpio_cd;
 	else
 		present = (mci_readl(slot->host, CDETECT) & (1 << slot->id))
@@ -2927,7 +2927,7 @@ static void dw_mci_enable_cd(struct dw_mci *host)
 		if (slot->mmc->caps & MMC_CAP_NEEDS_POLL)
 			return;
 
-		if (IS_ERR_VALUE(mmc_gpio_get_cd(slot->mmc)))
+		if (mmc_gpio_get_cd(slot->mmc) < 0)
 			break;
 	}
 	if (i == host->num_slots)
diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 2d300d87cda8..9d3ae1f4bd3c 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -1011,7 +1011,7 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev,
 	if (ret)
 		return ret;
 
-	if (!IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc)))
+	if (mmc_gpio_get_cd(host->mmc) >= 0)
 		host->quirks &= ~SDHCI_QUIRK_BROKEN_CARD_DETECTION;
 
 	return 0;
diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
index 25f779e09d8e..d4cef713d246 100644
--- a/drivers/mmc/host/sdhci-of-at91.c
+++ b/drivers/mmc/host/sdhci-of-at91.c
@@ -289,7 +289,7 @@ static int sdhci_at91_probe(struct platform_device *pdev)
 	 * to enable polling via device tree with broken-cd property.
 	 */
 	if (!(host->mmc->caps & MMC_CAP_NONREMOVABLE) &&
-	    IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc))) {
+	    mmc_gpio_get_cd(host->mmc) < 0) {
 		host->mmc->caps |= MMC_CAP_NEEDS_POLL;
 		host->quirks &= ~SDHCI_QUIRK_BROKEN_CARD_DETECTION;
 	}
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index e010ea4eb6f5..0e3d7c056cb1 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1624,7 +1624,7 @@ static int sdhci_get_cd(struct mmc_host *mmc)
 	 * Try slot gpio detect, if defined it take precedence
 	 * over build in controller functionality
 	 */
-	if (!IS_ERR_VALUE(gpio_cd))
+	if (gpio_cd >= 0)
 		return !!gpio_cd;
 
 	/* If polling, assume that the card is always present. */
@@ -3077,7 +3077,7 @@ int sdhci_add_host(struct sdhci_host *host)
 
 	if ((host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) &&
 	    !(mmc->caps & MMC_CAP_NONREMOVABLE) &&
-	    IS_ERR_VALUE(mmc_gpio_get_cd(host->mmc)))
+	    mmc_gpio_get_cd(host->mmc) < 0)
 		mmc->caps |= MMC_CAP_NEEDS_POLL;
 
 	/* If there are external regulators, get them */