netdev - Re: [RFC PATCH 1/2] net: ethtool: Add capability to retrieve plug-in module EEPROM

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Message-ID: <1334187728.2552.7.camel@bwh-desktop.uk.solarflarecom.com>
Date:	Thu, 12 Apr 2012 00:42:08 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Stuart Hodgson <smhodgson@...arflare.com>
CC:	<netdev@...r.kernel.org>, <bruce.w.allan@...el.com>,
	<mirq-linux@...e.qmqm.pl>, <decot@...gle.com>,
	<amit.salecha@...gic.com>, <alexander.h.duyck@...el.com>,
	<davem@...emloft.net>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] net: ethtool: Add capability to retrieve
 plug-in module EEPROM

On Wed, 2012-04-11 at 19:16 +0100, Ben Hutchings wrote:
> On Wed, 2012-04-11 at 17:50 +0100, Stuart Hodgson wrote:
> > On 02/04/12 18:52, Ben Hutchings wrote:
> [...]
> > >> --- a/net/core/ethtool.c
> > >> +++ b/net/core/ethtool.c
> [...]
> > >> +    if (eeprom.offset + eeprom.len>  modinfo.eeprom_len)
> > >> +        return -EINVAL;
> > >> +
> > >> +    data = kmalloc(PAGE_SIZE, GFP_USER);
> > >> +    if (!data)
> > >> +        return -ENOMEM;
> > >
> > > What if some device has a larger EEPROM?  Surely this length should be
> > > eeprom.len.
> > >
> > 
> > Do you mean what if the eeprom length in te device is larger than
> > PAGE_SIZE?
> 
> Yes.
> 
> > If so then it should really use modinfo.eeprom_len since
> > this the size of the data. eeprom.len could be arbitary.
> 
> No, eeprom.len is the size of the data and we've already validated it at
> this point.

Maybe we should start by refactoring ethtool_get_eeprom() so we can
reuse most of its code in ethtool_get_module_eeprom(), rather than
having to worry about what the maximum size of a module EEPROM might be
and whether we need a loop:

Subject: ethtool: Split ethtool_get_eeprom() to allow for additional EEPROM accessors

We want to support reading module (SFP+, XFP, ...) EEPROMs as well as
NIC EEPROMs.  They will need a different command number and driver
operation, but the structure and arguments will be the same and so we
can share most of the code here.

Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
---
 net/core/ethtool.c |   24 +++++++++++++++++-------
 1 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index beacdd9..ca7698f 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -751,18 +751,17 @@ static int ethtool_get_link(struct net_device *dev, char __user *useraddr)
 	return 0;
 }
 
-static int ethtool_get_eeprom(struct net_device *dev, void __user *useraddr)
+static int ethtool_get_any_eeprom(struct net_device *dev, void __user *useraddr,
+				  int (*getter)(struct net_device *,
+						struct ethtool_eeprom *, u8 *),
+				  u32 total_len)
 {
 	struct ethtool_eeprom eeprom;
-	const struct ethtool_ops *ops = dev->ethtool_ops;
 	void __user *userbuf = useraddr + sizeof(eeprom);
 	u32 bytes_remaining;
 	u8 *data;
 	int ret = 0;
 
-	if (!ops->get_eeprom || !ops->get_eeprom_len)
-		return -EOPNOTSUPP;
-
 	if (copy_from_user(&eeprom, useraddr, sizeof(eeprom)))
 		return -EFAULT;
 
@@ -771,7 +770,7 @@ static int ethtool_get_eeprom(struct net_device *dev, void __user *useraddr)
 		return -EINVAL;
 
 	/* Check for exceeding total eeprom len */
-	if (eeprom.offset + eeprom.len > ops->get_eeprom_len(dev))
+	if (eeprom.offset + eeprom.len > total_len)
 		return -EINVAL;
 
 	data = kmalloc(PAGE_SIZE, GFP_USER);
@@ -782,7 +781,7 @@ static int ethtool_get_eeprom(struct net_device *dev, void __user *useraddr)
 	while (bytes_remaining > 0) {
 		eeprom.len = min(bytes_remaining, (u32)PAGE_SIZE);
 
-		ret = ops->get_eeprom(dev, &eeprom, data);
+		ret = getter(dev, &eeprom, data);
 		if (ret)
 			break;
 		if (copy_to_user(userbuf, data, eeprom.len)) {
@@ -803,6 +802,17 @@ static int ethtool_get_eeprom(struct net_device *dev, void __user *useraddr)
 	return ret;
 }
 
+static int ethtool_get_eeprom(struct net_device *dev, void __user *useraddr)
+{
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+
+	if (!ops->get_eeprom || !ops->get_eeprom_len)
+		return -EOPNOTSUPP;
+
+	return ethtool_get_any_eeprom(dev, useraddr, ops->get_eeprom,
+				      ops->get_eeprom_len(dev));
+}
+
 static int ethtool_set_eeprom(struct net_device *dev, void __user *useraddr)
 {
 	struct ethtool_eeprom eeprom;
-- 
1.7.7.6

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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