linux-kernel - Re: [PATCH] PCI: xilinx-nwl: Simplify code and fix a memory leak

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Message-ID: <4d0576fb-0232-b165-bdef-e8a4310c6d29@wanadoo.fr>
Date:   Mon, 8 Nov 2021 07:37:29 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Krzysztof Wilczyński <kw@...ux.com>
Cc:     lorenzo.pieralisi@....com, robh@...nel.org, bhelgaas@...gle.com,
        michal.simek@...inx.com, linux-arm-kernel@...ts.infradead.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] PCI: xilinx-nwl: Simplify code and fix a memory leak

Le 08/11/2021 à 01:31, Krzysztof Wilczyński a écrit :
> Hi Christophe,
> 
>> Allocate space for 'bitmap' in 'struct nwl_msi' at build time instead of
>> dynamically allocating the memory at runtime.
>>
>> This simplifies code (especially error handling paths) and avoid some
>> open-coded arithmetic in allocator arguments
>>
>> This also fixes a potential memory leak. The bitmap was never freed. It is
>> now part of a managed resource.
> 
> Just to confirm - you mean potentially leaking when the driver would be
> unloaded?  Not the error handling path, correct?

Correct, the leak would happen on driver unload only.

CJ

> 
>> --- a/drivers/pci/controller/pcie-xilinx-nwl.c
>> +++ b/drivers/pci/controller/pcie-xilinx-nwl.c
>> @@ -146,7 +146,7 @@
>>   
>>   struct nwl_msi {			/* MSI information */
>>   	struct irq_domain *msi_domain;
>> -	unsigned long *bitmap;
>> +	DECLARE_BITMAP(bitmap, INT_PCI_MSI_NR);
>>   	struct irq_domain *dev_domain;
>>   	struct mutex lock;		/* protect bitmap variable */
>>   	int irq_msi0;
>> @@ -335,12 +335,10 @@ static void nwl_pcie_leg_handler(struct irq_desc *desc)
>>   
>>   static void nwl_pcie_handle_msi_irq(struct nwl_pcie *pcie, u32 status_reg)
>>   {
>> -	struct nwl_msi *msi;
>> +	struct nwl_msi *msi = &pcie->msi;
>>   	unsigned long status;
>>   	u32 bit;
>>   
>> -	msi = &pcie->msi;
>> -
>>   	while ((status = nwl_bridge_readl(pcie, status_reg)) != 0) {
>>   		for_each_set_bit(bit, &status, 32) {
>>   			nwl_bridge_writel(pcie, 1 << bit, status_reg);
>> @@ -560,30 +558,21 @@ static int nwl_pcie_enable_msi(struct nwl_pcie *pcie)
>>   	struct nwl_msi *msi = &pcie->msi;
>>   	unsigned long base;
>>   	int ret;
>> -	int size = BITS_TO_LONGS(INT_PCI_MSI_NR) * sizeof(long);
>>   
>>   	mutex_init(&msi->lock);
>>   
>> -	msi->bitmap = kzalloc(size, GFP_KERNEL);
>> -	if (!msi->bitmap)
>> -		return -ENOMEM;
>> -
>>   	/* Get msi_1 IRQ number */
>>   	msi->irq_msi1 = platform_get_irq_byname(pdev, "msi1");
>> -	if (msi->irq_msi1 < 0) {
>> -		ret = -EINVAL;
>> -		goto err;
>> -	}
>> +	if (msi->irq_msi1 < 0)
>> +		return -EINVAL;
>>   
>>   	irq_set_chained_handler_and_data(msi->irq_msi1,
>>   					 nwl_pcie_msi_handler_high, pcie);
>>   
>>   	/* Get msi_0 IRQ number */
>>   	msi->irq_msi0 = platform_get_irq_byname(pdev, "msi0");
>> -	if (msi->irq_msi0 < 0) {
>> -		ret = -EINVAL;
>> -		goto err;
>> -	}
>> +	if (msi->irq_msi0 < 0)
>> +		return -EINVAL;
>>   
>>   	irq_set_chained_handler_and_data(msi->irq_msi0,
>>   					 nwl_pcie_msi_handler_low, pcie);
>> @@ -592,8 +581,7 @@ static int nwl_pcie_enable_msi(struct nwl_pcie *pcie)
>>   	ret = nwl_bridge_readl(pcie, I_MSII_CAPABILITIES) & MSII_PRESENT;
>>   	if (!ret) {
>>   		dev_err(dev, "MSI not present\n");
>> -		ret = -EIO;
>> -		goto err;
>> +		return -EIO;
>>   	}
>>   
>>   	/* Enable MSII */
>> @@ -632,10 +620,6 @@ static int nwl_pcie_enable_msi(struct nwl_pcie *pcie)
>>   	nwl_bridge_writel(pcie, MSGF_MSI_SR_LO_MASK, MSGF_MSI_MASK_LO);
>>   
>>   	return 0;
>> -err:
>> -	kfree(msi->bitmap);
>> -	msi->bitmap = NULL;
>> -	return ret;
> 
> Thank you!
> 
> Reviewed-by: Krzysztof Wilczyński <kw@...ux.com>
> 
> 	Krzysztof
>