Re: [PATCH] Remove lots of IS_ERR_VALUE abuses.

From: Arnd Bergmann
Date: Thu Jul 07 2016 - 04:07:24 EST

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On Thursday, July 7, 2016 12:47:43 AM CEST Arvind Yadav 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.
>
> 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 gigabit ethernet driver.
>
> 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.
>
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@xxxxxxxxx>

The above is my changelog text for commit 287980e49f, but it's not my patch.

Your changes look fine, but reusing my description there seems wrong.
Can you add a new description and just point to my commit instead?

Arnd

> drivers/net/ethernet/freescale/ucc_geth.c | 30 +++++++++++++++---------------
> 1 file changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/ucc_geth.c b/drivers/net/ethernet/freescale/ucc_geth.c
> index 5bf1ade..c1ead2c 100644
> --- a/drivers/net/ethernet/freescale/ucc_geth.c
> +++ b/drivers/net/ethernet/freescale/ucc_geth.c
> @@ -289,7 +289,7 @@ static int fill_init_enet_entries(struct ucc_geth_private *ugeth,
> else {
> init_enet_offset =
> qe_muram_alloc(thread_size, thread_alignment);
> - if (IS_ERR_VALUE(init_enet_offset)) {
> + if (init_enet_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory\n");
> qe_put_snum((u8) snum);
> @@ -2234,7 +2234,7 @@ static int ucc_geth_alloc_tx(struct ucc_geth_private *ugeth)
> ugeth->tx_bd_ring_offset[j] =
> qe_muram_alloc(length,
> UCC_GETH_TX_BD_RING_ALIGNMENT);
> - if (!IS_ERR_VALUE(ugeth->tx_bd_ring_offset[j]))
> + if (!ugeth->tx_bd_ring_offset[j])
> ugeth->p_tx_bd_ring[j] =
> (u8 __iomem *) qe_muram_addr(ugeth->
> tx_bd_ring_offset[j]);
> @@ -2311,7 +2311,7 @@ static int ucc_geth_alloc_rx(struct ucc_geth_private *ugeth)
> ugeth->rx_bd_ring_offset[j] =
> qe_muram_alloc(length,
> UCC_GETH_RX_BD_RING_ALIGNMENT);
> - if (!IS_ERR_VALUE(ugeth->rx_bd_ring_offset[j]))
> + if (!ugeth->rx_bd_ring_offset[j])
> ugeth->p_rx_bd_ring[j] =
> (u8 __iomem *) qe_muram_addr(ugeth->
> rx_bd_ring_offset[j]);
> @@ -2521,7 +2521,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> ugeth->tx_glbl_pram_offset =
> qe_muram_alloc(sizeof(struct ucc_geth_tx_global_pram),
> UCC_GETH_TX_GLOBAL_PRAM_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->tx_glbl_pram_offset)) {
> + if (ugeth->tx_glbl_pram_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_tx_glbl_pram\n");
> return -ENOMEM;
> @@ -2541,7 +2541,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> sizeof(struct ucc_geth_thread_data_tx) +
> 32 * (numThreadsTxNumerical == 1),
> UCC_GETH_THREAD_DATA_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->thread_dat_tx_offset)) {
> + if (ugeth->thread_dat_tx_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_thread_data_tx\n");
> return -ENOMEM;
> @@ -2568,7 +2568,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> qe_muram_alloc(ug_info->numQueuesTx *
> sizeof(struct ucc_geth_send_queue_qd),
> UCC_GETH_SEND_QUEUE_QUEUE_DESCRIPTOR_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->send_q_mem_reg_offset)) {
> + if (ugeth->send_q_mem_reg_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_send_q_mem_reg\n");
> return -ENOMEM;
> @@ -2609,7 +2609,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> ugeth->scheduler_offset =
> qe_muram_alloc(sizeof(struct ucc_geth_scheduler),
> UCC_GETH_SCHEDULER_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->scheduler_offset)) {
> + if (ugeth->scheduler_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_scheduler\n");
> return -ENOMEM;
> @@ -2656,7 +2656,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> qe_muram_alloc(sizeof
> (struct ucc_geth_tx_firmware_statistics_pram),
> UCC_GETH_TX_STATISTICS_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->tx_fw_statistics_pram_offset)) {
> + if (ugeth->tx_fw_statistics_pram_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_tx_fw_statistics_pram\n");
> return -ENOMEM;
> @@ -2693,7 +2693,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> ugeth->rx_glbl_pram_offset =
> qe_muram_alloc(sizeof(struct ucc_geth_rx_global_pram),
> UCC_GETH_RX_GLOBAL_PRAM_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->rx_glbl_pram_offset)) {
> + if (ugeth->rx_glbl_pram_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_rx_glbl_pram\n");
> return -ENOMEM;
> @@ -2712,7 +2712,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> qe_muram_alloc(numThreadsRxNumerical *
> sizeof(struct ucc_geth_thread_data_rx),
> UCC_GETH_THREAD_DATA_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->thread_dat_rx_offset)) {
> + if (ugeth->thread_dat_rx_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_thread_data_rx\n");
> return -ENOMEM;
> @@ -2733,7 +2733,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> qe_muram_alloc(sizeof
> (struct ucc_geth_rx_firmware_statistics_pram),
> UCC_GETH_RX_STATISTICS_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->rx_fw_statistics_pram_offset)) {
> + if (ugeth->rx_fw_statistics_pram_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_rx_fw_statistics_pram\n");
> return -ENOMEM;
> @@ -2753,7 +2753,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> qe_muram_alloc(ug_info->numQueuesRx *
> sizeof(struct ucc_geth_rx_interrupt_coalescing_entry)
> + 4, UCC_GETH_RX_INTERRUPT_COALESCING_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->rx_irq_coalescing_tbl_offset)) {
> + if (ugeth->rx_irq_coalescing_tbl_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_rx_irq_coalescing_tbl\n");
> return -ENOMEM;
> @@ -2819,7 +2819,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> (sizeof(struct ucc_geth_rx_bd_queues_entry) +
> sizeof(struct ucc_geth_rx_prefetched_bds)),
> UCC_GETH_RX_BD_QUEUES_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->rx_bd_qs_tbl_offset)) {
> + if (ugeth->rx_bd_qs_tbl_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_rx_bd_qs_tbl\n");
> return -ENOMEM;
> @@ -2905,7 +2905,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
> ugeth->exf_glbl_param_offset =
> qe_muram_alloc(sizeof(struct ucc_geth_exf_global_pram),
> UCC_GETH_RX_EXTENDED_FILTERING_GLOBAL_PARAMETERS_ALIGNMENT);
> - if (IS_ERR_VALUE(ugeth->exf_glbl_param_offset)) {
> + if (ugeth->exf_glbl_param_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_exf_glbl_param\n");
> return -ENOMEM;
> @@ -3039,7 +3039,7 @@ static int ucc_geth_startup(struct ucc_geth_private *ugeth)
>
> /* Allocate InitEnet command parameter structure */
> init_enet_pram_offset = qe_muram_alloc(sizeof(struct ucc_geth_init_pram), 4);
> - if (IS_ERR_VALUE(init_enet_pram_offset)) {
> + if (init_enet_pram_offset < 0) {
> if (netif_msg_ifup(ugeth))
> pr_err("Can not allocate DPRAM memory for p_init_enet_pram\n");
> return -ENOMEM;
>

Next message: Jan Beulich: "[PATCH] xenbus: prefer xenbus_scanf() over xenbus_gather()"
Previous message: Jan Beulich: "[PATCH] xen-blkfront: prefer xenbus_write() over xenbus_printf() where possible"
In reply to: Arvind Yadav: "[PATCH] Remove lots of IS_ERR_VALUE abuses."
Next in thread: arvind Yadav: "Re: [PATCH] Remove lots of IS_ERR_VALUE abuses."
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