diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/RCU/rculist_nulls.txt | 167 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 7 | ||||
| -rw-r--r-- | Documentation/networking/README.ipw2200 | 2 | ||||
| -rw-r--r-- | Documentation/networking/bonding.txt | 68 | ||||
| -rw-r--r-- | Documentation/networking/dccp.txt | 7 | ||||
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 6 | ||||
| -rw-r--r-- | Documentation/networking/regulatory.txt | 22 | ||||
| -rw-r--r-- | Documentation/rfkill.txt | 20 |
8 files changed, 261 insertions, 38 deletions
diff --git a/Documentation/RCU/rculist_nulls.txt b/Documentation/RCU/rculist_nulls.txt new file mode 100644 index 00000000000..239f542d48b --- /dev/null +++ b/Documentation/RCU/rculist_nulls.txt @@ -0,0 +1,167 @@ +Using hlist_nulls to protect read-mostly linked lists and +objects using SLAB_DESTROY_BY_RCU allocations. + +Please read the basics in Documentation/RCU/listRCU.txt + +Using special makers (called 'nulls') is a convenient way +to solve following problem : + +A typical RCU linked list managing objects which are +allocated with SLAB_DESTROY_BY_RCU kmem_cache can +use following algos : + +1) Lookup algo +-------------- +rcu_read_lock() +begin: +obj = lockless_lookup(key); +if (obj) { + if (!try_get_ref(obj)) // might fail for free objects + goto begin; + /* + * Because a writer could delete object, and a writer could + * reuse these object before the RCU grace period, we + * must check key after geting the reference on object + */ + if (obj->key != key) { // not the object we expected + put_ref(obj); + goto begin; + } +} +rcu_read_unlock(); + +Beware that lockless_lookup(key) cannot use traditional hlist_for_each_entry_rcu() +but a version with an additional memory barrier (smp_rmb()) + +lockless_lookup(key) +{ + struct hlist_node *node, *next; + for (pos = rcu_dereference((head)->first); + pos && ({ next = pos->next; smp_rmb(); prefetch(next); 1; }) && + ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); + pos = rcu_dereference(next)) + if (obj->key == key) + return obj; + return NULL; + +And note the traditional hlist_for_each_entry_rcu() misses this smp_rmb() : + + struct hlist_node *node; + for (pos = rcu_dereference((head)->first); + pos && ({ prefetch(pos->next); 1; }) && + ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); + pos = rcu_dereference(pos->next)) + if (obj->key == key) + return obj; + return NULL; +} + +Quoting Corey Minyard : + +"If the object is moved from one list to another list in-between the + time the hash is calculated and the next field is accessed, and the + object has moved to the end of a new list, the traversal will not + complete properly on the list it should have, since the object will + be on the end of the new list and there's not a way to tell it's on a + new list and restart the list traversal. I think that this can be + solved by pre-fetching the "next" field (with proper barriers) before + checking the key." + +2) Insert algo : +---------------- + +We need to make sure a reader cannot read the new 'obj->obj_next' value +and previous value of 'obj->key'. Or else, an item could be deleted +from a chain, and inserted into another chain. If new chain was empty +before the move, 'next' pointer is NULL, and lockless reader can +not detect it missed following items in original chain. + +/* + * Please note that new inserts are done at the head of list, + * not in the middle or end. + */ +obj = kmem_cache_alloc(...); +lock_chain(); // typically a spin_lock() +obj->key = key; +atomic_inc(&obj->refcnt); +/* + * we need to make sure obj->key is updated before obj->next + */ +smp_wmb(); +hlist_add_head_rcu(&obj->obj_node, list); +unlock_chain(); // typically a spin_unlock() + + +3) Remove algo +-------------- +Nothing special here, we can use a standard RCU hlist deletion. +But thanks to SLAB_DESTROY_BY_RCU, beware a deleted object can be reused +very very fast (before the end of RCU grace period) + +if (put_last_reference_on(obj) { + lock_chain(); // typically a spin_lock() + hlist_del_init_rcu(&obj->obj_node); + unlock_chain(); // typically a spin_unlock() + kmem_cache_free(cachep, obj); +} + + + +-------------------------------------------------------------------------- +With hlist_nulls we can avoid extra smp_rmb() in lockless_lookup() +and extra smp_wmb() in insert function. + +For example, if we choose to store the slot number as the 'nulls' +end-of-list marker for each slot of the hash table, we can detect +a race (some writer did a delete and/or a move of an object +to another chain) checking the final 'nulls' value if +the lookup met the end of chain. If final 'nulls' value +is not the slot number, then we must restart the lookup at +the begining. If the object was moved to same chain, +then the reader doesnt care : It might eventually +scan the list again without harm. + + +1) lookup algo + + head = &table[slot]; + rcu_read_lock(); +begin: + hlist_nulls_for_each_entry_rcu(obj, node, head, member) { + if (obj->key == key) { + if (!try_get_ref(obj)) // might fail for free objects + goto begin; + if (obj->key != key) { // not the object we expected + put_ref(obj); + goto begin; + } + goto out; + } +/* + * if the nulls value we got at the end of this lookup is + * not the expected one, we must restart lookup. + * We probably met an item that was moved to another chain. + */ + if (get_nulls_value(node) != slot) + goto begin; + obj = NULL; + +out: + rcu_read_unlock(); + +2) Insert function : +-------------------- + +/* + * Please note that new inserts are done at the head of list, + * not in the middle or end. + */ +obj = kmem_cache_alloc(cachep); +lock_chain(); // typically a spin_lock() +obj->key = key; +atomic_set(&obj->refcnt, 1); +/* + * insert obj in RCU way (readers might be traversing chain) + */ +hlist_nulls_add_head_rcu(&obj->obj_node, list); +unlock_chain(); // typically a spin_unlock() diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index c28a2ac88f9..77eb6b129dd 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -120,13 +120,6 @@ Who: Christoph Hellwig <hch@lst.de> --------------------------- -What: eepro100 network driver -When: January 2007 -Why: replaced by the e100 driver -Who: Adrian Bunk <bunk@stusta.de> - ---------------------------- - What: Unused EXPORT_SYMBOL/EXPORT_SYMBOL_GPL exports (temporary transition config option provided until then) The transition config option will also be removed at the same time. diff --git a/Documentation/networking/README.ipw2200 b/Documentation/networking/README.ipw2200 index 4f2a40f1dbc..80c728522c4 100644 --- a/Documentation/networking/README.ipw2200 +++ b/Documentation/networking/README.ipw2200 @@ -147,7 +147,7 @@ Where the supported parameter are: driver. If disabled, the driver will not attempt to scan for and associate to a network until it has been configured with one or more properties for the target network, for example configuring - the network SSID. Default is 1 (auto-associate) + the network SSID. Default is 0 (do not auto-associate) Example: % modprobe ipw2200 associate=0 diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt index 688dfe1e6b7..5ede7473b42 100644 --- a/Documentation/networking/bonding.txt +++ b/Documentation/networking/bonding.txt @@ -194,6 +194,48 @@ or, for backwards compatibility, the option value. E.g., The parameters are as follows: +ad_select + + Specifies the 802.3ad aggregation selection logic to use. The + possible values and their effects are: + + stable or 0 + + The active aggregator is chosen by largest aggregate + bandwidth. + + Reselection of the active aggregator occurs only when all + slaves of the active aggregator are down or the active + aggregator has no slaves. + + This is the default value. + + bandwidth or 1 + + The active aggregator is chosen by largest aggregate + bandwidth. Reselection occurs if: + + - A slave is added to or removed from the bond + + - Any slave's link state changes + + - Any slave's 802.3ad association state changes + + - The bond's adminstrative state changes to up + + count or 2 + + The active aggregator is chosen by the largest number of + ports (slaves). Reselection occurs as described under the + "bandwidth" setting, above. + + The bandwidth and count selection policies permit failover of + 802.3ad aggregations when partial failure of the active aggregator + occurs. This keeps the aggregator with the highest availability + (either in bandwidth or in number of ports) active at all times. + + This option was added in bonding version 3.4.0. + arp_interval Specifies the ARP link monitoring frequency in milliseconds. @@ -551,6 +593,16 @@ num_grat_arp affects only the active-backup mode. This option was added for bonding version 3.3.0. +num_unsol_na + + Specifies the number of unsolicited IPv6 Neighbor Advertisements + to be issued after a failover event. One unsolicited NA is issued + immediately after the failover. + + The valid range is 0 - 255; the default value is 1. This option + affects only the active-backup mode. This option was added for + bonding version 3.4.0. + primary A string (eth0, eth2, etc) specifying which slave is the @@ -922,17 +974,19 @@ USERCTL=no NETMASK, NETWORK and BROADCAST) to match your network configuration. For later versions of initscripts, such as that found with Fedora -7 and Red Hat Enterprise Linux version 5 (or later), it is possible, and, -indeed, preferable, to specify the bonding options in the ifcfg-bond0 +7 (or later) and Red Hat Enterprise Linux version 5 (or later), it is possible, +and, indeed, preferable, to specify the bonding options in the ifcfg-bond0 file, e.g. a line of the format: -BONDING_OPTS="mode=active-backup arp_interval=60 arp_ip_target=+192.168.1.254" +BONDING_OPTS="mode=active-backup arp_interval=60 arp_ip_target=192.168.1.254" will configure the bond with the specified options. The options specified in BONDING_OPTS are identical to the bonding module parameters -except for the arp_ip_target field. Each target should be included as a -separate option and should be preceded by a '+' to indicate it should be -added to the list of queried targets, e.g., +except for the arp_ip_target field when using versions of initscripts older +than and 8.57 (Fedora 8) and 8.45.19 (Red Hat Enterprise Linux 5.2). When +using older versions each target should be included as a separate option and +should be preceded by a '+' to indicate it should be added to the list of +queried targets, e.g., arp_ip_target=+192.168.1.1 arp_ip_target=+192.168.1.2 @@ -940,7 +994,7 @@ added to the list of queried targets, e.g., options via BONDING_OPTS, it is not necessary to edit /etc/modules.conf or /etc/modprobe.conf. - For older versions of initscripts that do not support + For even older versions of initscripts that do not support BONDING_OPTS, it is necessary to edit /etc/modules.conf (or /etc/modprobe.conf, depending upon your distro) to load the bonding module with your desired options when the bond0 interface is brought up. The diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt index 39131a3c78f..43df4487379 100644 --- a/Documentation/networking/dccp.txt +++ b/Documentation/networking/dccp.txt @@ -57,6 +57,10 @@ can be set before calling bind(). DCCP_SOCKOPT_GET_CUR_MPS is read-only and retrieves the current maximum packet size (application payload size) in bytes, see RFC 4340, section 14. +DCCP_SOCKOPT_AVAILABLE_CCIDS is also read-only and returns the list of CCIDs +supported by the endpoint (see include/linux/dccp.h for symbolic constants). +The caller needs to provide a sufficiently large (> 2) array of type uint8_t. + DCCP_SOCKOPT_SERVER_TIMEWAIT enables the server (listening socket) to hold timewait state when closing the connection (RFC 4340, 8.3). The usual case is that the closing server sends a CloseReq, whereupon the client holds timewait @@ -121,9 +125,6 @@ send_ndp = 1 send_ackvec = 1 Whether or not to send Ack Vector options (sec. 11.5). -ack_ratio = 2 - The default Ack Ratio (sec. 11.3) to use. - tx_ccid = 2 Default CCID for the sender-receiver half-connection. diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index d84932650fd..c7712787933 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -27,6 +27,12 @@ min_adv_mss - INTEGER The advertised MSS depends on the first hop route MTU, but will never be lower than this setting. +rt_cache_rebuild_count - INTEGER + The per net-namespace route cache emergency rebuild threshold. + Any net-namespace having its route cache rebuilt due to + a hash bucket chain being too long more than this many times + will have its route caching disabled + IP Fragmentation: ipfrag_high_thresh - INTEGER diff --git a/Documentation/networking/regulatory.txt b/Documentation/networking/regulatory.txt index a96989a8ff3..dcf31648414 100644 --- a/Documentation/networking/regulatory.txt +++ b/Documentation/networking/regulatory.txt @@ -131,11 +131,13 @@ are expected to do this during initialization. r = zd_reg2alpha2(mac->regdomain, alpha2); if (!r) - regulatory_hint(hw->wiphy, alpha2, NULL); + regulatory_hint(hw->wiphy, alpha2); Example code - drivers providing a built in regulatory domain: -------------------------------------------------------------- +[NOTE: This API is not currently available, it can be added when required] + If you have regulatory information you can obtain from your driver and you *need* to use this we let you build a regulatory domain structure and pass it to the wireless core. To do this you should @@ -167,7 +169,6 @@ struct ieee80211_regdomain mydriver_jp_regdom = { Then in some part of your code after your wiphy has been registered: - int r; struct ieee80211_regdomain *rd; int size_of_regd; int num_rules = mydriver_jp_regdom.n_reg_rules; @@ -178,17 +179,12 @@ Then in some part of your code after your wiphy has been registered: rd = kzalloc(size_of_regd, GFP_KERNEL); if (!rd) - return -ENOMEM; + return -ENOMEM; memcpy(rd, &mydriver_jp_regdom, sizeof(struct ieee80211_regdomain)); - for (i=0; i < num_rules; i++) { - memcpy(&rd->reg_rules[i], &mydriver_jp_regdom.reg_rules[i], - sizeof(struct ieee80211_reg_rule)); - } - r = regulatory_hint(hw->wiphy, NULL, rd); - if (r) { - kfree(rd); - return r; - } - + for (i=0; i < num_rules; i++) + memcpy(&rd->reg_rules[i], + &mydriver_jp_regdom.reg_rules[i], + sizeof(struct ieee80211_reg_rule)); + regulatory_struct_hint(rd); diff --git a/Documentation/rfkill.txt b/Documentation/rfkill.txt index b65f0799df4..4d3ee317a4a 100644 --- a/Documentation/rfkill.txt +++ b/Documentation/rfkill.txt @@ -191,12 +191,20 @@ Userspace input handlers (uevents) or kernel input handlers (rfkill-input): to tell the devices registered with the rfkill class to change their state (i.e. translates the input layer event into real action). + * rfkill-input implements EPO by handling EV_SW SW_RFKILL_ALL 0 (power off all transmitters) in a special way: it ignores any overrides and local state cache and forces all transmitters to the RFKILL_STATE_SOFT_BLOCKED state (including those which are already - supposed to be BLOCKED). Note that the opposite event (power on all - transmitters) is handled normally. + supposed to be BLOCKED). + * rfkill EPO will remain active until rfkill-input receives an + EV_SW SW_RFKILL_ALL 1 event. While the EPO is active, transmitters + are locked in the blocked state (rfkill will refuse to unblock them). + * rfkill-input implements different policies that the user can + select for handling EV_SW SW_RFKILL_ALL 1. It will unlock rfkill, + and either do nothing (leave transmitters blocked, but now unlocked), + restore the transmitters to their state before the EPO, or unblock + them all. Userspace uevent handler or kernel platform-specific drivers hooked to the rfkill notifier chain: @@ -331,11 +339,9 @@ class to get a sysfs interface :-) correct event for your switch/button. These events are emergency power-off events when they are trying to turn the transmitters off. An example of an input device which SHOULD generate *_RFKILL_ALL events is the wireless-kill -switch in a laptop which is NOT a hotkey, but a real switch that kills radios -in hardware, even if the O.S. has gone to lunch. An example of an input device -which SHOULD NOT generate *_RFKILL_ALL events by default, is any sort of hot -key that does nothing by itself, as well as any hot key that is type-specific -(e.g. the one for WLAN). +switch in a laptop which is NOT a hotkey, but a real sliding/rocker switch. +An example of an input device which SHOULD NOT generate *_RFKILL_ALL events by +default, is any sort of hot key that is type-specific (e.g. the one for WLAN). 3.1 Guidelines for wireless device drivers |