ACK: [PATCH 1/1] iwlwifi: pcie: don't warn if we use all the transmit pointers

[Stefan Bader]

On 03.01.19 07:42, Kai-Heng Feng wrote:
> From: Emmanuel Grumbach <emmanuel.grumbach at intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1801102
> 
> Our Transmit Frame Descriptor (TFD) is a DMA descriptor that
> includes several pointers to be able to transmit a packet
> which is not physically contiguous.
> 
> Depending on the hardware being use, we can have 20 or 25
> pointers in a single TFD. In both cases, it is more than
> enough and it is quite hard to hit this limit.
> It has been reported that when using specific applications
> (Ktorrent), we can actually use all the pointers and then
> a long standing bug showed up.
> 
> When we free the TFD, we check its number of valid pointers
> and make sure it doesn't exceed the number of pointers the
> hardware support.
> This check had an off by one bug: it is perfectly valid to
> free the 20 pointers if the TFD has 20 pointers.
> 
> Fix that.
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=197981
> 
> Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach at intel.com>
> Signed-off-by: Luca Coelho <luciano.coelho at intel.com>
> (cherry picked from commit 4437ba7ee7de7e71d11deb91c87a370e4ffd2601)
> Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c | 2 +-
>  drivers/net/wireless/intel/iwlwifi/pcie/tx.c      | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
> index 6d0a907d5ba5..fabae0f60683 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
> @@ -147,7 +147,7 @@ static void iwl_pcie_gen2_tfd_unmap(struct iwl_trans *trans,
>  	/* Sanity check on number of chunks */
>  	num_tbs = iwl_pcie_gen2_get_num_tbs(trans, tfd);
>  
> -	if (num_tbs >= trans_pcie->max_tbs) {
> +	if (num_tbs > trans_pcie->max_tbs) {
>  		IWL_ERR(trans, "Too many chunks: %i\n", num_tbs);
>  		return;
>  	}
> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c
> index 3f85713c41dc..1a566287993d 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/tx.c
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx.c
> @@ -378,7 +378,7 @@ static void iwl_pcie_tfd_unmap(struct iwl_trans *trans,
>  	/* Sanity check on number of chunks */
>  	num_tbs = iwl_pcie_tfd_get_num_tbs(trans, tfd);
>  
> -	if (num_tbs >= trans_pcie->max_tbs) {
> +	if (num_tbs > trans_pcie->max_tbs) {
>  		IWL_ERR(trans, "Too many chunks: %i\n", num_tbs);
>  		/* @todo issue fatal error, it is quite serious situation */
>  		return;
> 


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