* [RFC] mac80211: Fix MAX MTU Calculation [not found] <201212201236.qBKCakFZ011657@chaitanya-desktop> @ 2012-12-20 12:43 ` Chaitanya 2012-12-20 13:07 ` Johannes Berg 0 siblings, 1 reply; 3+ messages in thread From: Chaitanya @ 2012-12-20 12:43 UTC (permalink / raw) To: Johannes Berg; +Cc: linux-wireless Fix the MTU calculation, we should check for data_len+ mesh hdr len and shouldn't include any header lengths. ToDo: Get the MAX_DATA_LEN based on driver's AMSDU capability. Signed-off-by: T Krishna Chaitanya <chaitanyatk@posedge.com> --- net/mac80211/iface.c | 17 ++++++++++++++++- 1 files changed, 16 insertions(+), 1 deletions(-) diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c index 54fb7f9..da74ef9 100644 --- a/net/mac80211/iface.c +++ b/net/mac80211/iface.c @@ -214,8 +214,23 @@ static int ieee80211_change_mtu(struct net_device *dev, int new_mtu) /* FIX: what would be proper limits for MTU? * This interface uses 802.3 frames. */ + /* Fixed: MTU needn't worry about headers*/ + + /* 802.11-2012: 8.2.3: The maximum frame body size is determined by + 1. The maximum MSDU size (2304 octets), + 2. plus the length of the Mesh Control field (6, 12, or 18 octets) + if present, + 3. the maximum unencrypted MMPDU size excluding the MAC header and + FCS (2304 octets) or + 4. the maximum A- MSDU size (3839 or 7935 octets), + plus any overhead from security encapsulation. + Note1: IEEE80211_MAX_DATA_LEN doesnt include any headers (2304), + so it can be used directly+ Mesh HDR Len + Note2: In Other places (like skb_alloc) its handled properly. + */ + if (new_mtu < 256 || - new_mtu > IEEE80211_MAX_DATA_LEN - 24 - 6 - meshhdrlen) { + new_mtu > IEEE80211_MAX_DATA_LEN + meshhdrlen) { return -EINVAL; } ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC] mac80211: Fix MAX MTU Calculation 2012-12-20 12:43 ` [RFC] mac80211: Fix MAX MTU Calculation Chaitanya @ 2012-12-20 13:07 ` Johannes Berg 2012-12-20 13:17 ` Chaitanya 0 siblings, 1 reply; 3+ messages in thread From: Johannes Berg @ 2012-12-20 13:07 UTC (permalink / raw) To: Chaitanya; +Cc: linux-wireless On Thu, 2012-12-20 at 18:13 +0530, Chaitanya wrote: > Fix the MTU calculation, we should check for data_len+ mesh hdr len > and shouldn't include any header lengths. > > ToDo: Get the MAX_DATA_LEN based on driver's AMSDU capability. > > Signed-off-by: T Krishna Chaitanya <chaitanyatk@posedge.com> > > --- > > net/mac80211/iface.c | 17 ++++++++++++++++- > 1 files changed, 16 insertions(+), 1 deletions(-) > > diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c > index 54fb7f9..da74ef9 100644 > --- a/net/mac80211/iface.c > +++ b/net/mac80211/iface.c > @@ -214,8 +214,23 @@ static int ieee80211_change_mtu(struct net_device *dev, int new_mtu) > > /* FIX: what would be proper limits for MTU? > * This interface uses 802.3 frames. */ > + /* Fixed: MTU needn't worry about headers*/ > + > + /* 802.11-2012: 8.2.3: The maximum frame body size is determined by > + 1. The maximum MSDU size (2304 octets), > + 2. plus the length of the Mesh Control field (6, 12, or 18 octets) > + if present, > + 3. the maximum unencrypted MMPDU size excluding the MAC header and > + FCS (2304 octets) or > + 4. the maximum A- MSDU size (3839 or 7935 octets), > + plus any overhead from security encapsulation. > + Note1: IEEE80211_MAX_DATA_LEN doesnt include any headers (2304), > + so it can be used directly+ Mesh HDR Len > + Note2: In Other places (like skb_alloc) its handled properly. > + */ > + ok so the comment style is wrong, you shouldn't list changelog-type things in comments ("Fixed: ...") etc. I also don't understand why we should add the mesh length? It seems that this is really just the maximum MSDU size, i.e. 2304 octets. johannes ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC] mac80211: Fix MAX MTU Calculation 2012-12-20 13:07 ` Johannes Berg @ 2012-12-20 13:17 ` Chaitanya 0 siblings, 0 replies; 3+ messages in thread From: Chaitanya @ 2012-12-20 13:17 UTC (permalink / raw) To: Johannes Berg; +Cc: linux-wireless On Thursday 20 December 2012 06:37 PM, Johannes Berg wrote: > On Thu, 2012-12-20 at 18:13 +0530, Chaitanya wrote: >> Fix the MTU calculation, we should check for data_len+ mesh hdr len >> and shouldn't include any header lengths. >> >> ToDo: Get the MAX_DATA_LEN based on driver's AMSDU capability. >> >> Signed-off-by: T Krishna Chaitanya <chaitanyatk@posedge.com> >> >> --- >> >> net/mac80211/iface.c | 17 ++++++++++++++++- >> 1 files changed, 16 insertions(+), 1 deletions(-) >> >> diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c >> index 54fb7f9..da74ef9 100644 >> --- a/net/mac80211/iface.c >> +++ b/net/mac80211/iface.c >> @@ -214,8 +214,23 @@ static int ieee80211_change_mtu(struct net_device *dev, int new_mtu) >> >> /* FIX: what would be proper limits for MTU? >> * This interface uses 802.3 frames. */ >> + /* Fixed: MTU needn't worry about headers*/ >> + >> + /* 802.11-2012: 8.2.3: The maximum frame body size is determined by >> + 1. The maximum MSDU size (2304 octets), >> + 2. plus the length of the Mesh Control field (6, 12, or 18 octets) >> + if present, >> + 3. the maximum unencrypted MMPDU size excluding the MAC header and >> + FCS (2304 octets) or >> + 4. the maximum A- MSDU size (3839 or 7935 octets), >> + plus any overhead from security encapsulation. >> + Note1: IEEE80211_MAX_DATA_LEN doesnt include any headers (2304), >> + so it can be used directly+ Mesh HDR Len >> + Note2: In Other places (like skb_alloc) its handled properly. >> + */ >> + > ok so the comment style is wrong, you shouldn't list changelog-type > things in comments ("Fixed: ...") etc. > > I also don't understand why we should add the mesh length? It seems that > this is really just the maximum MSDU size, i.e. 2304 octets. > > johannes > Ok, will change the comments. So shall i remove the comments for FIX as well (or) should i retain them? As for WLAN is concerned the mesh header is part of data (MSDU) hence the standard says the MSDU can be Maximum of 2304 + Any Mesh Control Field. (#2 above). ^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-12-20 12:43 ` [RFC] mac80211: Fix MAX MTU Calculation Chaitanya
2012-12-20 13:07 ` Johannes Berg
2012-12-20 13:17 ` Chaitanya
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