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Subject: Re: [PATCH v2 01/14] PCI: Use sysfs_emit() and sysfs_emit_at() in
 "show" functions
From: Joe Perches <joe@perches.com>
To: Krzysztof =?UTF-8?Q?Wilczy=C5=84ski?= <kw@linux.com>, Bjorn Helgaas
 <bhelgaas@google.com>
Date: Fri, 14 May 2021 22:43:35 -0700
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References: <20210515052434.1413236-1-kw@linux.com>
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Cc: Tyrel Datwyler <tyreld@linux.ibm.com>, linux-pci@vger.kernel.org,
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On Sat, 2021-05-15 at 05:24 +0000, Krzysztof Wilczyński wrote:
> The sysfs_emit() and sysfs_emit_at() functions were introduced to make
> it less ambiguous which function is preferred when writing to the output
> buffer in a device attribute's "show" callback [1].
> 
> Convert the PCI sysfs object "show" functions from sprintf(), snprintf()
> and scnprintf() to sysfs_emit() and sysfs_emit_at() accordingly, as the
> latter is aware of the PAGE_SIZE buffer and correctly returns the number
> of bytes written into the buffer.
[]
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
[]
> @@ -6439,7 +6439,7 @@ static ssize_t resource_alignment_show(struct bus_type *bus, char *buf)
>  
> 
>  	spin_lock(&resource_alignment_lock);
>  	if (resource_alignment_param)
> -		count = scnprintf(buf, PAGE_SIZE, "%s", resource_alignment_param);
> +		count = sysfs_emit(buf, "%s", resource_alignment_param);
>  	spin_unlock(&resource_alignment_lock);

Ideally, the additional newline check below this would use sysfs_emit_at

drivers/pci/pci.c-      /*
drivers/pci/pci.c:       * When set by the command line, resource_alignment_param will not
drivers/pci/pci.c-       * have a trailing line feed, which is ugly. So conditionally add
drivers/pci/pci.c-       * it here.
drivers/pci/pci.c-       */
drivers/pci/pci.c-      if (count >= 2 && buf[count - 2] != '\n' && count < PAGE_SIZE - 1) {
drivers/pci/pci.c-              buf[count - 1] = '\n';
drivers/pci/pci.c-              buf[count++] = 0;
drivers/pci/pci.c-      }
drivers/pci/pci.c-
drivers/pci/pci.c-      return count;