linux-kernel - Re: [PATCH] PCI: Remove redundant TTL variable initialization

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Message-ID: <d5d12494-aa17-4012-8265-3c91981611c4@163.com>
Date: Sat, 16 Aug 2025 23:54:02 +0800
From: Hans Zhang <18255117159@....com>
To: bhelgaas@...gle.com
Cc: ilpo.jarvinen@...ux.intel.com, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: Remove redundant TTL variable initialization

Dear Bjorn,

Because of this series, you have accepted it.
https://patchwork.kernel.org/project/linux-pci/cover/20250813144529.303548-1-18255117159@163.com/

It is already in the following branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/log/?h=capability-search


But I saw the status of patch as "Not Applicable". Is it necessary for 
me to remake the v2 version based on v6.17-rc1? Or is this patch 
unreasonable?

Best regards,
Hans

On 2025/6/16 23:24, Hans Zhang wrote:
> The local variables `ttl` were initialized to PCI_FIND_CAP_TTL but never
> actually used. The loop termination condition is inherently controlled
> by the TTL mechanism inside the PCI_FIND_NEXT_CAP_TTL macro, which already
> ensures protection against infinite loops.
> 
> Remove these redundant operations to simplify the code and eliminate
> potential logical ambiguities. This change does not affect functionality,
> as the TTL safeguard is properly implemented within the macro.
> 
> Signed-off-by: Hans Zhang <18255117159@....com>
> ---
> - Submissions based on the following patches:
> https://patchwork.kernel.org/project/linux-pci/patch/20250607161405.808585-1-18255117159@163.com/
> 
> Recently, I checked the code and found that there are still some areas that can be further optimized.
> The above series of patches has been around for a long time, so I'm sending this one out for review
> as a separate patch.
> ---
>   drivers/pci/quirks.c | 17 ++++++++---------
>   1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index d7f4ee634263..50d0f193e4a3 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -2742,10 +2742,10 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x9601, quirk_amd_780_apc_msi);
>    */
>   static int msi_ht_cap_enabled(struct pci_dev *dev)
>   {
> -	int pos, ttl = PCI_FIND_CAP_TTL;
> +	int pos;
>   
>   	pos = pci_find_ht_capability(dev, HT_CAPTYPE_MSI_MAPPING);
> -	while (pos && ttl--) {
> +	while (pos) {
>   		u8 flags;
>   
>   		if (pci_read_config_byte(dev, pos + HT_MSI_FLAGS,
> @@ -2796,10 +2796,10 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_CK804_PCIE,
>   /* Force enable MSI mapping capability on HT bridges */
>   static void ht_enable_msi_mapping(struct pci_dev *dev)
>   {
> -	int pos, ttl = PCI_FIND_CAP_TTL;
> +	int pos;
>   
>   	pos = pci_find_ht_capability(dev, HT_CAPTYPE_MSI_MAPPING);
> -	while (pos && ttl--) {
> +	while (pos) {
>   		u8 flags;
>   
>   		if (pci_read_config_byte(dev, pos + HT_MSI_FLAGS,
> @@ -2935,12 +2935,11 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA,
>   
>   static int ht_check_msi_mapping(struct pci_dev *dev)
>   {
> -	int pos, ttl = PCI_FIND_CAP_TTL;
> -	int found = 0;
> +	int pos, found = 0;
>   
>   	/* Check if there is HT MSI cap or enabled on this device */
>   	pos = pci_find_ht_capability(dev, HT_CAPTYPE_MSI_MAPPING);
> -	while (pos && ttl--) {
> +	while (pos) {
>   		u8 flags;
>   
>   		if (found < 1)
> @@ -3060,10 +3059,10 @@ static void nv_ht_enable_msi_mapping(struct pci_dev *dev)
>   
>   static void ht_disable_msi_mapping(struct pci_dev *dev)
>   {
> -	int pos, ttl = PCI_FIND_CAP_TTL;
> +	int pos;
>   
>   	pos = pci_find_ht_capability(dev, HT_CAPTYPE_MSI_MAPPING);
> -	while (pos && ttl--) {
> +	while (pos) {
>   		u8 flags;
>   
>   		if (pci_read_config_byte(dev, pos + HT_MSI_FLAGS,
> 
> base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494