diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devices.txt | 5 | ||||
| -rw-r--r-- | Documentation/memory-barriers.txt | 4 | ||||
| -rw-r--r-- | Documentation/networking/operstates.txt | 161 | ||||
| -rw-r--r-- | Documentation/scsi/ChangeLog.megaraid | 25 |
4 files changed, 188 insertions, 7 deletions
diff --git a/Documentation/devices.txt b/Documentation/devices.txt index 3c406acd4df..b369a8c46a7 100644 --- a/Documentation/devices.txt +++ b/Documentation/devices.txt @@ -1721,11 +1721,6 @@ Your cooperation is appreciated. These devices support the same API as the generic SCSI devices. - 97 block Packet writing for CD/DVD devices - 0 = /dev/pktcdvd0 First packet-writing module - 1 = /dev/pktcdvd1 Second packet-writing module - ... - 98 char Control and Measurement Device (comedi) 0 = /dev/comedi0 First comedi device 1 = /dev/comedi1 Second comedi device diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index 92f0056d928..c61d8b876fd 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1031,7 +1031,7 @@ conflict on any particular lock. LOCKS VS MEMORY ACCESSES ------------------------ -Consider the following: the system has a pair of spinlocks (N) and (Q), and +Consider the following: the system has a pair of spinlocks (M) and (Q), and three CPUs; then should the following sequence of events occur: CPU 1 CPU 2 @@ -1678,7 +1678,7 @@ CPU's caches by some other cache event: smp_wmb(); <A:modify v=2> <C:busy> <C:queue v=2> - p = &b; q = p; + p = &v; q = p; <D:request p> <B:modify p=&v> <D:commit p=&v> <D:read p> diff --git a/Documentation/networking/operstates.txt b/Documentation/networking/operstates.txt new file mode 100644 index 00000000000..4a21d9bb836 --- /dev/null +++ b/Documentation/networking/operstates.txt @@ -0,0 +1,161 @@ + +1. Introduction + +Linux distinguishes between administrative and operational state of an +interface. Admininstrative state is the result of "ip link set dev +<dev> up or down" and reflects whether the administrator wants to use +the device for traffic. + +However, an interface is not usable just because the admin enabled it +- ethernet requires to be plugged into the switch and, depending on +a site's networking policy and configuration, an 802.1X authentication +to be performed before user data can be transferred. Operational state +shows the ability of an interface to transmit this user data. + +Thanks to 802.1X, userspace must be granted the possibility to +influence operational state. To accommodate this, operational state is +split into two parts: Two flags that can be set by the driver only, and +a RFC2863 compatible state that is derived from these flags, a policy, +and changeable from userspace under certain rules. + + +2. Querying from userspace + +Both admin and operational state can be queried via the netlink +operation RTM_GETLINK. It is also possible to subscribe to RTMGRP_LINK +to be notified of updates. This is important for setting from userspace. + +These values contain interface state: + +ifinfomsg::if_flags & IFF_UP: + Interface is admin up +ifinfomsg::if_flags & IFF_RUNNING: + Interface is in RFC2863 operational state UP or UNKNOWN. This is for + backward compatibility, routing daemons, dhcp clients can use this + flag to determine whether they should use the interface. +ifinfomsg::if_flags & IFF_LOWER_UP: + Driver has signaled netif_carrier_on() +ifinfomsg::if_flags & IFF_DORMANT: + Driver has signaled netif_dormant_on() + +These interface flags can also be queried without netlink using the +SIOCGIFFLAGS ioctl. + +TLV IFLA_OPERSTATE + +contains RFC2863 state of the interface in numeric representation: + +IF_OPER_UNKNOWN (0): + Interface is in unknown state, neither driver nor userspace has set + operational state. Interface must be considered for user data as + setting operational state has not been implemented in every driver. +IF_OPER_NOTPRESENT (1): + Unused in current kernel (notpresent interfaces normally disappear), + just a numerical placeholder. +IF_OPER_DOWN (2): + Interface is unable to transfer data on L1, f.e. ethernet is not + plugged or interface is ADMIN down. +IF_OPER_LOWERLAYERDOWN (3): + Interfaces stacked on an interface that is IF_OPER_DOWN show this + state (f.e. VLAN). +IF_OPER_TESTING (4): + Unused in current kernel. +IF_OPER_DORMANT (5): + Interface is L1 up, but waiting for an external event, f.e. for a + protocol to establish. (802.1X) +IF_OPER_UP (6): + Interface is operational up and can be used. + +This TLV can also be queried via sysfs. + +TLV IFLA_LINKMODE + +contains link policy. This is needed for userspace interaction +described below. + +This TLV can also be queried via sysfs. + + +3. Kernel driver API + +Kernel drivers have access to two flags that map to IFF_LOWER_UP and +IFF_DORMANT. These flags can be set from everywhere, even from +interrupts. It is guaranteed that only the driver has write access, +however, if different layers of the driver manipulate the same flag, +the driver has to provide the synchronisation needed. + +__LINK_STATE_NOCARRIER, maps to !IFF_LOWER_UP: + +The driver uses netif_carrier_on() to clear and netif_carrier_off() to +set this flag. On netif_carrier_off(), the scheduler stops sending +packets. The name 'carrier' and the inversion are historical, think of +it as lower layer. + +netif_carrier_ok() can be used to query that bit. + +__LINK_STATE_DORMANT, maps to IFF_DORMANT: + +Set by the driver to express that the device cannot yet be used +because some driver controlled protocol establishment has to +complete. Corresponding functions are netif_dormant_on() to set the +flag, netif_dormant_off() to clear it and netif_dormant() to query. + +On device allocation, networking core sets the flags equivalent to +netif_carrier_ok() and !netif_dormant(). + + +Whenever the driver CHANGES one of these flags, a workqueue event is +scheduled to translate the flag combination to IFLA_OPERSTATE as +follows: + +!netif_carrier_ok(): + IF_OPER_LOWERLAYERDOWN if the interface is stacked, IF_OPER_DOWN + otherwise. Kernel can recognise stacked interfaces because their + ifindex != iflink. + +netif_carrier_ok() && netif_dormant(): + IF_OPER_DORMANT + +netif_carrier_ok() && !netif_dormant(): + IF_OPER_UP if userspace interaction is disabled. Otherwise + IF_OPER_DORMANT with the possibility for userspace to initiate the + IF_OPER_UP transition afterwards. + + +4. Setting from userspace + +Applications have to use the netlink interface to influence the +RFC2863 operational state of an interface. Setting IFLA_LINKMODE to 1 +via RTM_SETLINK instructs the kernel that an interface should go to +IF_OPER_DORMANT instead of IF_OPER_UP when the combination +netif_carrier_ok() && !netif_dormant() is set by the +driver. Afterwards, the userspace application can set IFLA_OPERSTATE +to IF_OPER_DORMANT or IF_OPER_UP as long as the driver does not set +netif_carrier_off() or netif_dormant_on(). Changes made by userspace +are multicasted on the netlink group RTMGRP_LINK. + +So basically a 802.1X supplicant interacts with the kernel like this: + +-subscribe to RTMGRP_LINK +-set IFLA_LINKMODE to 1 via RTM_SETLINK +-query RTM_GETLINK once to get initial state +-if initial flags are not (IFF_LOWER_UP && !IFF_DORMANT), wait until + netlink multicast signals this state +-do 802.1X, eventually abort if flags go down again +-send RTM_SETLINK to set operstate to IF_OPER_UP if authentication + succeeds, IF_OPER_DORMANT otherwise +-see how operstate and IFF_RUNNING is echoed via netlink multicast +-set interface back to IF_OPER_DORMANT if 802.1X reauthentication + fails +-restart if kernel changes IFF_LOWER_UP or IFF_DORMANT flag + +if supplicant goes down, bring back IFLA_LINKMODE to 0 and +IFLA_OPERSTATE to a sane value. + +A routing daemon or dhcp client just needs to care for IFF_RUNNING or +waiting for operstate to go IF_OPER_UP/IF_OPER_UNKNOWN before +considering the interface / querying a DHCP address. + + +For technical questions and/or comments please e-mail to Stefan Rompf +(stefan at loplof.de). diff --git a/Documentation/scsi/ChangeLog.megaraid b/Documentation/scsi/ChangeLog.megaraid index 09f6300eda4..c173806c91f 100644 --- a/Documentation/scsi/ChangeLog.megaraid +++ b/Documentation/scsi/ChangeLog.megaraid @@ -1,3 +1,28 @@ +Release Date : Mon Apr 11 12:27:22 EST 2006 - Seokmann Ju <sju@lsil.com> +Current Version : 2.20.4.8 (scsi module), 2.20.2.6 (cmm module) +Older Version : 2.20.4.7 (scsi module), 2.20.2.6 (cmm module) + +1. Fixed a bug in megaraid_reset_handler(). + Customer reported "Unable to handle kernel NULL pointer dereference + at virtual address 00000000" when system goes to reset condition + for some reason. It happened randomly. + Root Cause: in the megaraid_reset_handler(), there is possibility not + returning pending packets in the pend_list if there are multiple + pending packets. + Fix: Made the change in the driver so that it will return all packets + in the pend_list. + +2. Added change request. + As found in the following URL, rmb() only didn't help the + problem. I had to increase the loop counter to 0xFFFFFF. (6 F's) + http://marc.theaimsgroup.com/?l=linux-scsi&m=110971060502497&w=2 + + I attached a patch for your reference, too. + Could you check and get this fix in your driver? + + Best Regards, + Jun'ichi Nomura + Release Date : Fri Nov 11 12:27:22 EST 2005 - Seokmann Ju <sju@lsil.com> Current Version : 2.20.4.7 (scsi module), 2.20.2.6 (cmm module) Older Version : 2.20.4.6 (scsi module), 2.20.2.6 (cmm module) |