diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-driver-usb-usbtmc | 14 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-block-rssd | 18 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-cfq-target-latency | 8 | ||||
| -rw-r--r-- | Documentation/DMA-attributes.txt | 18 | ||||
| -rw-r--r-- | Documentation/DocBook/device-drivers.tmpl | 17 | ||||
| -rw-r--r-- | Documentation/cgroups/cpusets.txt | 2 | ||||
| -rw-r--r-- | Documentation/cgroups/memory.txt | 5 | ||||
| -rw-r--r-- | Documentation/cpu-hotplug.txt | 22 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/mtd/atmel-nand.txt | 10 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/regulator/anatop-regulator.txt | 29 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 16 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 2 | ||||
| -rw-r--r-- | Documentation/hwmon/k10temp | 2 | ||||
| -rw-r--r-- | Documentation/ioctl/ioctl-number.txt | 1 | ||||
| -rw-r--r-- | Documentation/networking/driver.txt | 31 | ||||
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 11 | ||||
| -rw-r--r-- | Documentation/networking/netdevices.txt | 25 | ||||
| -rw-r--r-- | Documentation/usb/URB.txt | 22 | ||||
| -rw-r--r-- | Documentation/usb/usbmon.txt | 6 |
19 files changed, 181 insertions, 78 deletions
diff --git a/Documentation/ABI/stable/sysfs-driver-usb-usbtmc b/Documentation/ABI/stable/sysfs-driver-usb-usbtmc index 2a7f9a0..e960cd0 100644 --- a/Documentation/ABI/stable/sysfs-driver-usb-usbtmc +++ b/Documentation/ABI/stable/sysfs-driver-usb-usbtmc @@ -1,5 +1,5 @@ -What: /sys/bus/usb/drivers/usbtmc/devices/*/interface_capabilities -What: /sys/bus/usb/drivers/usbtmc/devices/*/device_capabilities +What: /sys/bus/usb/drivers/usbtmc/*/interface_capabilities +What: /sys/bus/usb/drivers/usbtmc/*/device_capabilities Date: August 2008 Contact: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Description: @@ -12,8 +12,8 @@ Description: The files are read only. -What: /sys/bus/usb/drivers/usbtmc/devices/*/usb488_interface_capabilities -What: /sys/bus/usb/drivers/usbtmc/devices/*/usb488_device_capabilities +What: /sys/bus/usb/drivers/usbtmc/*/usb488_interface_capabilities +What: /sys/bus/usb/drivers/usbtmc/*/usb488_device_capabilities Date: August 2008 Contact: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Description: @@ -27,7 +27,7 @@ Description: The files are read only. -What: /sys/bus/usb/drivers/usbtmc/devices/*/TermChar +What: /sys/bus/usb/drivers/usbtmc/*/TermChar Date: August 2008 Contact: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Description: @@ -40,7 +40,7 @@ Description: sent to the device or not. -What: /sys/bus/usb/drivers/usbtmc/devices/*/TermCharEnabled +What: /sys/bus/usb/drivers/usbtmc/*/TermCharEnabled Date: August 2008 Contact: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Description: @@ -51,7 +51,7 @@ Description: published by the USB-IF. -What: /sys/bus/usb/drivers/usbtmc/devices/*/auto_abort +What: /sys/bus/usb/drivers/usbtmc/*/auto_abort Date: August 2008 Contact: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Description: diff --git a/Documentation/ABI/testing/sysfs-block-rssd b/Documentation/ABI/testing/sysfs-block-rssd new file mode 100644 index 0000000..d535757 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-block-rssd @@ -0,0 +1,18 @@ +What: /sys/block/rssd*/registers +Date: March 2012 +KernelVersion: 3.3 +Contact: Asai Thambi S P <asamymuthupa@micron.com> +Description: This is a read-only file. Dumps below driver information and + hardware registers. + - S ACTive + - Command Issue + - Allocated + - Completed + - PORT IRQ STAT + - HOST IRQ STAT + +What: /sys/block/rssd*/status +Date: April 2012 +KernelVersion: 3.4 +Contact: Asai Thambi S P <asamymuthupa@micron.com> +Description: This is a read-only file. Indicates the status of the device. diff --git a/Documentation/ABI/testing/sysfs-cfq-target-latency b/Documentation/ABI/testing/sysfs-cfq-target-latency new file mode 100644 index 0000000..df0f782 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-cfq-target-latency @@ -0,0 +1,8 @@ +What: /sys/block/<device>/iosched/target_latency +Date: March 2012 +contact: Tao Ma <boyu.mt@taobao.com> +Description: + The /sys/block/<device>/iosched/target_latency only exists + when the user sets cfq to /sys/block/<device>/scheduler. + It contains an estimated latency time for the cfq. cfq will + use it to calculate the time slice used for every task. diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt index b768cc0..5c72eed 100644 --- a/Documentation/DMA-attributes.txt +++ b/Documentation/DMA-attributes.txt @@ -31,3 +31,21 @@ may be weakly ordered, that is that reads and writes may pass each other. Since it is optional for platforms to implement DMA_ATTR_WEAK_ORDERING, those that do not will simply ignore the attribute and exhibit default behavior. + +DMA_ATTR_WRITE_COMBINE +---------------------- + +DMA_ATTR_WRITE_COMBINE specifies that writes to the mapping may be +buffered to improve performance. + +Since it is optional for platforms to implement DMA_ATTR_WRITE_COMBINE, +those that do not will simply ignore the attribute and exhibit default +behavior. + +DMA_ATTR_NON_CONSISTENT +----------------------- + +DMA_ATTR_NON_CONSISTENT lets the platform to choose to return either +consistent or non-consistent memory as it sees fit. By using this API, +you are guaranteeing to the platform that you have all the correct and +necessary sync points for this memory in the driver. diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl index 9c27e51..7514dbf 100644 --- a/Documentation/DocBook/device-drivers.tmpl +++ b/Documentation/DocBook/device-drivers.tmpl @@ -446,4 +446,21 @@ X!Idrivers/video/console/fonts.c !Edrivers/i2c/i2c-core.c </chapter> + <chapter id="hsi"> + <title>High Speed Synchronous Serial Interface (HSI)</title> + + <para> + High Speed Synchronous Serial Interface (HSI) is a + serial interface mainly used for connecting application + engines (APE) with cellular modem engines (CMT) in cellular + handsets. + + HSI provides multiplexing for up to 16 logical channels, + low-latency and full duplex communication. + </para> + +!Iinclude/linux/hsi/hsi.h +!Edrivers/hsi/hsi.c + </chapter> + </book> diff --git a/Documentation/cgroups/cpusets.txt b/Documentation/cgroups/cpusets.txt index 5c51ed4..cefd3d8 100644 --- a/Documentation/cgroups/cpusets.txt +++ b/Documentation/cgroups/cpusets.txt @@ -217,7 +217,7 @@ and name space for cpusets, with a minimum of additional kernel code. The cpus and mems files in the root (top_cpuset) cpuset are read-only. The cpus file automatically tracks the value of -cpu_online_map using a CPU hotplug notifier, and the mems file +cpu_online_mask using a CPU hotplug notifier, and the mems file automatically tracks the value of node_states[N_HIGH_MEMORY]--i.e., nodes with memory--using the cpuset_track_online_nodes() hook. diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 4c95c00..9b1067a 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -34,8 +34,7 @@ Current Status: linux-2.6.34-mmotm(development version of 2010/April) Features: - accounting anonymous pages, file caches, swap caches usage and limiting them. - - private LRU and reclaim routine. (system's global LRU and private LRU - work independently from each other) + - pages are linked to per-memcg LRU exclusively, and there is no global LRU. - optionally, memory+swap usage can be accounted and limited. - hierarchical accounting - soft limit @@ -154,7 +153,7 @@ updated. page_cgroup has its own LRU on cgroup. 2.2.1 Accounting details All mapped anon pages (RSS) and cache pages (Page Cache) are accounted. -Some pages which are never reclaimable and will not be on the global LRU +Some pages which are never reclaimable and will not be on the LRU are not accounted. We just account pages under usual VM management. RSS pages are accounted at page_fault unless they've already been accounted diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt index a20bfd4..66ef8f3 100644 --- a/Documentation/cpu-hotplug.txt +++ b/Documentation/cpu-hotplug.txt @@ -47,7 +47,7 @@ maxcpus=n Restrict boot time cpus to n. Say if you have 4 cpus, using other cpus later online, read FAQ's for more info. additional_cpus=n (*) Use this to limit hotpluggable cpus. This option sets - cpu_possible_map = cpu_present_map + additional_cpus + cpu_possible_mask = cpu_present_mask + additional_cpus cede_offline={"off","on"} Use this option to disable/enable putting offlined processors to an extended H_CEDE state on @@ -64,11 +64,11 @@ should only rely on this to count the # of cpus, but *MUST* not rely on the apicid values in those tables for disabled apics. In the event BIOS doesn't mark such hot-pluggable cpus as disabled entries, one could use this parameter "additional_cpus=x" to represent those cpus in the -cpu_possible_map. +cpu_possible_mask. possible_cpus=n [s390,x86_64] use this to set hotpluggable cpus. This option sets possible_cpus bits in - cpu_possible_map. Thus keeping the numbers of bits set + cpu_possible_mask. Thus keeping the numbers of bits set constant even if the machine gets rebooted. CPU maps and such @@ -76,7 +76,7 @@ CPU maps and such [More on cpumaps and primitive to manipulate, please check include/linux/cpumask.h that has more descriptive text.] -cpu_possible_map: Bitmap of possible CPUs that can ever be available in the +cpu_possible_mask: Bitmap of possible CPUs that can ever be available in the system. This is used to allocate some boot time memory for per_cpu variables that aren't designed to grow/shrink as CPUs are made available or removed. Once set during boot time discovery phase, the map is static, i.e no bits @@ -84,13 +84,13 @@ are added or removed anytime. Trimming it accurately for your system needs upfront can save some boot time memory. See below for how we use heuristics in x86_64 case to keep this under check. -cpu_online_map: Bitmap of all CPUs currently online. Its set in __cpu_up() +cpu_online_mask: Bitmap of all CPUs currently online. Its set in __cpu_up() after a cpu is available for kernel scheduling and ready to receive interrupts from devices. Its cleared when a cpu is brought down using __cpu_disable(), before which all OS services including interrupts are migrated to another target CPU. -cpu_present_map: Bitmap of CPUs currently present in the system. Not all +cpu_present_mask: Bitmap of CPUs currently present in the system. Not all of them may be online. When physical hotplug is processed by the relevant subsystem (e.g ACPI) can change and new bit either be added or removed from the map depending on the event is hot-add/hot-remove. There are currently @@ -99,22 +99,22 @@ at which time hotplug is disabled. You really dont need to manipulate any of the system cpu maps. They should be read-only for most use. When setting up per-cpu resources almost always use -cpu_possible_map/for_each_possible_cpu() to iterate. +cpu_possible_mask/for_each_possible_cpu() to iterate. Never use anything other than cpumask_t to represent bitmap of CPUs. #include <linux/cpumask.h> - for_each_possible_cpu - Iterate over cpu_possible_map - for_each_online_cpu - Iterate over cpu_online_map - for_each_present_cpu - Iterate over cpu_present_map + for_each_possible_cpu - Iterate over cpu_possible_mask + for_each_online_cpu - Iterate over cpu_online_mask + for_each_present_cpu - Iterate over cpu_present_mask for_each_cpu_mask(x,mask) - Iterate over some random collection of cpu mask. #include <linux/cpu.h> get_online_cpus() and put_online_cpus(): The above calls are used to inhibit cpu hotplug operations. While the -cpu_hotplug.refcount is non zero, the cpu_online_map will not change. +cpu_hotplug.refcount is non zero, the cpu_online_mask will not change. If you merely need to avoid cpus going away, you could also use preempt_disable() and preempt_enable() for those sections. Just remember the critical section cannot call any diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand.txt b/Documentation/devicetree/bindings/mtd/atmel-nand.txt index 5903ecf..a200695 100644 --- a/Documentation/devicetree/bindings/mtd/atmel-nand.txt +++ b/Documentation/devicetree/bindings/mtd/atmel-nand.txt @@ -27,13 +27,13 @@ nand0: nand@40000000,0 { reg = <0x40000000 0x10000000 0xffffe800 0x200 >; - atmel,nand-addr-offset = <21>; - atmel,nand-cmd-offset = <22>; + atmel,nand-addr-offset = <21>; /* ale */ + atmel,nand-cmd-offset = <22>; /* cle */ nand-on-flash-bbt; nand-ecc-mode = "soft"; - gpios = <&pioC 13 0 - &pioC 14 0 - 0 + gpios = <&pioC 13 0 /* rdy */ + &pioC 14 0 /* nce */ + 0 /* cd */ >; partition@0 { ... diff --git a/Documentation/devicetree/bindings/regulator/anatop-regulator.txt b/Documentation/devicetree/bindings/regulator/anatop-regulator.txt new file mode 100644 index 0000000..357758c --- /dev/null +++ b/Documentation/devicetree/bindings/regulator/anatop-regulator.txt @@ -0,0 +1,29 @@ +Anatop Voltage regulators + +Required properties: +- compatible: Must be "fsl,anatop-regulator" +- anatop-reg-offset: Anatop MFD register offset +- anatop-vol-bit-shift: Bit shift for the register +- anatop-vol-bit-width: Number of bits used in the register +- anatop-min-bit-val: Minimum value of this register +- anatop-min-voltage: Minimum voltage of this regulator +- anatop-max-voltage: Maximum voltage of this regulator + +Any property defined as part of the core regulator +binding, defined in regulator.txt, can also be used. + +Example: + + regulator-vddpu { + compatible = "fsl,anatop-regulator"; + regulator-name = "vddpu"; + regulator-min-microvolt = <725000>; + regulator-max-microvolt = <1300000>; + regulator-always-on; + anatop-reg-offset = <0x140>; + anatop-vol-bit-shift = <9>; + anatop-vol-bit-width = <5>; + anatop-min-bit-val = <1>; + anatop-min-voltage = <725000>; + anatop-max-voltage = <1300000>; + }; diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index c1be806..03ca210 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -6,14 +6,6 @@ be removed from this file. --------------------------- -What: x86 floppy disable_hlt -When: 2012 -Why: ancient workaround of dubious utility clutters the - code used by everybody else. -Who: Len Brown <len.brown@intel.com> - ---------------------------- - What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle When: 2012 Why: This optional sub-feature of APM is of dubious reliability, @@ -539,3 +531,11 @@ Why: There appear to be no production users of the get_robust_list syscall, of ASLR. It was only ever intended for debugging, so it should be removed. Who: Kees Cook <keescook@chromium.org> + +---------------------------- + +What: setitimer accepts user NULL pointer (value) +When: 3.6 +Why: setitimer is not returning -EFAULT if user pointer is NULL. This + violates the spec. +Who: Sasikantha Babu <sasikanth.v19@gmail.com> diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index e916e3d..0d04920 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -114,7 +114,7 @@ members are defined: struct file_system_type { const char *name; int fs_flags; - struct dentry (*mount) (struct file_system_type *, int, + struct dentry *(*mount) (struct file_system_type *, int, const char *, void *); void (*kill_sb) (struct super_block *); struct module *owner; diff --git a/Documentation/hwmon/k10temp b/Documentation/hwmon/k10temp index a10f736..90956b6 100644 --- a/Documentation/hwmon/k10temp +++ b/Documentation/hwmon/k10temp @@ -11,7 +11,7 @@ Supported chips: Socket S1G2: Athlon (X2), Sempron (X2), Turion X2 (Ultra) * AMD Family 12h processors: "Llano" (E2/A4/A6/A8-Series) * AMD Family 14h processors: "Brazos" (C/E/G/Z-Series) -* AMD Family 15h processors: "Bulldozer" +* AMD Family 15h processors: "Bulldozer" (FX-Series), "Trinity" Prefix: 'k10temp' Addresses scanned: PCI space diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt index 3b7488f..e34b531d 100644 --- a/Documentation/ioctl/ioctl-number.txt +++ b/Documentation/ioctl/ioctl-number.txt @@ -225,6 +225,7 @@ Code Seq#(hex) Include File Comments 'j' 00-3F linux/joystick.h 'k' 00-0F linux/spi/spidev.h conflict! 'k' 00-05 video/kyro.h conflict! +'k' 10-17 linux/hsi/hsi_char.h HSI character device 'l' 00-3F linux/tcfs_fs.h transparent cryptographic file system <http://web.archive.org/web/*/http://mikonos.dia.unisa.it/tcfs> 'l' 40-7F linux/udf_fs_i.h in development: diff --git a/Documentation/networking/driver.txt b/Documentation/networking/driver.txt index 03283da..da59e28 100644 --- a/Documentation/networking/driver.txt +++ b/Documentation/networking/driver.txt @@ -2,16 +2,16 @@ Document about softnet driver issues Transmit path guidelines: -1) The hard_start_xmit method must never return '1' under any - normal circumstances. It is considered a hard error unless +1) The ndo_start_xmit method must not return NETDEV_TX_BUSY under + any normal circumstances. It is considered a hard error unless there is no way your device can tell ahead of time when it's transmit function will become busy. Instead it must maintain the queue properly. For example, for a driver implementing scatter-gather this means: - static int drv_hard_start_xmit(struct sk_buff *skb, - struct net_device *dev) + static netdev_tx_t drv_hard_start_xmit(struct sk_buff *skb, + struct net_device *dev) { struct drv *dp = netdev_priv(dev); @@ -23,7 +23,7 @@ Transmit path guidelines: unlock_tx(dp); printk(KERN_ERR PFX "%s: BUG! Tx Ring full when queue awake!\n", dev->name); - return 1; + return NETDEV_TX_BUSY; } ... queue packet to card ... @@ -35,6 +35,7 @@ Transmit path guidelines: ... unlock_tx(dp); ... + return NETDEV_TX_OK; } And then at the end of your TX reclamation event handling: @@ -58,15 +59,12 @@ Transmit path guidelines: TX_BUFFS_AVAIL(dp) > 0) netif_wake_queue(dp->dev); -2) Do not forget to update netdev->trans_start to jiffies after - each new tx packet is given to the hardware. - -3) A hard_start_xmit method must not modify the shared parts of a +2) An ndo_start_xmit method must not modify the shared parts of a cloned SKB. -4) Do not forget that once you return 0 from your hard_start_xmit - method, it is your driver's responsibility to free up the SKB - and in some finite amount of time. +3) Do not forget that once you return NETDEV_TX_OK from your + ndo_start_xmit method, it is your driver's responsibility to free + up the SKB and in some finite amount of time. For example, this means that it is not allowed for your TX mitigation scheme to let TX packets "hang out" in the TX @@ -74,8 +72,9 @@ Transmit path guidelines: This error can deadlock sockets waiting for send buffer room to be freed up. - If you return 1 from the hard_start_xmit method, you must not keep - any reference to that SKB and you must not attempt to free it up. + If you return NETDEV_TX_BUSY from the ndo_start_xmit method, you + must not keep any reference to that SKB and you must not attempt + to free it up. Probing guidelines: @@ -85,10 +84,10 @@ Probing guidelines: Close/stop guidelines: -1) After the dev->stop routine has been called, the hardware must +1) After the ndo_stop routine has been called, the hardware must not receive or transmit any data. All in flight packets must be aborted. If necessary, poll or wait for completion of any reset commands. -2) The dev->stop routine will be called by unregister_netdevice +2) The ndo_stop routine will be called by unregister_netdevice if device is still UP. diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index ad3e80e..bd80ba5 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -604,15 +604,8 @@ IP Variables: ip_local_port_range - 2 INTEGERS Defines the local port range that is used by TCP and UDP to choose the local port. The first number is the first, the - second the last local port number. Default value depends on - amount of memory available on the system: - > 128Mb 32768-61000 - < 128Mb 1024-4999 or even less. - This number defines number of active connections, which this - system can issue simultaneously to systems not supporting - TCP extensions (timestamps). With tcp_tw_recycle enabled - (i.e. by default) range 1024-4999 is enough to issue up to - 2000 connections per second to systems supporting timestamps. + second the last local port number. The default values are + 32768 and 61000 respectively. ip_local_reserved_ports - list of comma separated ranges Specify the ports which are reserved for known third-party diff --git a/Documentation/networking/netdevices.txt b/Documentation/networking/netdevices.txt index 8935834..c7ecc70 100644 --- a/Documentation/networking/netdevices.txt +++ b/Documentation/networking/netdevices.txt @@ -47,26 +47,25 @@ packets is preferred. struct net_device synchronization rules ======================================= -dev->open: +ndo_open: Synchronization: rtnl_lock() semaphore. Context: process -dev->stop: +ndo_stop: Synchronization: rtnl_lock() semaphore. Context: process - Note1: netif_running() is guaranteed false - Note2: dev->poll() is guaranteed to be stopped + Note: netif_running() is guaranteed false -dev->do_ioctl: +ndo_do_ioctl: Synchronization: rtnl_lock() semaphore. Context: process -dev->get_stats: +ndo_get_stats: Synchronization: dev_base_lock rwlock. Context: nominally process, but don't sleep inside an rwlock -dev->hard_start_xmit: - Synchronization: netif_tx_lock spinlock. +ndo_start_xmit: + Synchronization: __netif_tx_lock spinlock. When the driver sets NETIF_F_LLTX in dev->features this will be called without holding netif_tx_lock. In this case the driver @@ -87,20 +86,20 @@ dev->hard_start_xmit: o NETDEV_TX_LOCKED Locking failed, please retry quickly. Only valid when NETIF_F_LLTX is set. -dev->tx_timeout: - Synchronization: netif_tx_lock spinlock. +ndo_tx_timeout: + Synchronization: netif_tx_lock spinlock; all TX queues frozen. Context: BHs disabled Notes: netif_queue_stopped() is guaranteed true -dev->set_rx_mode: - Synchronization: netif_tx_lock spinlock. +ndo_set_rx_mode: + Synchronization: netif_addr_lock spinlock. Context: BHs disabled struct napi_struct synchronization rules ======================================== napi->poll: Synchronization: NAPI_STATE_SCHED bit in napi->state. Device - driver's dev->close method will invoke napi_disable() on + driver's ndo_stop method will invoke napi_disable() on all NAPI instances which will do a sleeping poll on the NAPI_STATE_SCHED napi->state bit, waiting for all pending NAPI activity to cease. diff --git a/Documentation/usb/URB.txt b/Documentation/usb/URB.txt index 8ffce74..00d2c64 100644 --- a/Documentation/usb/URB.txt +++ b/Documentation/usb/URB.txt @@ -168,6 +168,28 @@ that if the completion handler or anyone else tries to resubmit it they will get a -EPERM error. Thus you can be sure that when usb_kill_urb() returns, the URB is totally idle. +There is a lifetime issue to consider. An URB may complete at any +time, and the completion handler may free the URB. If this happens +while usb_unlink_urb or usb_kill_urb is running, it will cause a +memory-access violation. The driver is responsible for avoiding this, +which often means some sort of lock will be needed to prevent the URB +from being deallocated while it is still in use. + +On the other hand, since usb_unlink_urb may end up calling the +completion handler, the handler must not take any lock that is held +when usb_unlink_urb is invoked. The general solution to this problem +is to increment the URB's reference count while holding the lock, then +drop the lock and call usb_unlink_urb or usb_kill_urb, and then +decrement the URB's reference count. You increment the reference +count by calling + + struct urb *usb_get_urb(struct urb *urb) + +(ignore the return value; it is the same as the argument) and +decrement the reference count by calling usb_free_urb. Of course, +none of this is necessary if there's no danger of the URB being freed +by the completion handler. + 1.7. What about the completion handler? diff --git a/Documentation/usb/usbmon.txt b/Documentation/usb/usbmon.txt index 5335fa8..c42bb9c 100644 --- a/Documentation/usb/usbmon.txt +++ b/Documentation/usb/usbmon.txt @@ -183,10 +183,10 @@ An input control transfer to get a port status. d5ea89a0 3575914555 S Ci:1:001:0 s a3 00 0000 0003 0004 4 < d5ea89a0 3575914560 C Ci:1:001:0 0 4 = 01050000 -An output bulk transfer to send a SCSI command 0x5E in a 31-byte Bulk wrapper -to a storage device at address 5: +An output bulk transfer to send a SCSI command 0x28 (READ_10) in a 31-byte +Bulk wrapper to a storage device at address 5: -dd65f0e8 4128379752 S Bo:1:005:2 -115 31 = 55534243 5e000000 00000000 00000600 00000000 00000000 00000000 000000 +dd65f0e8 4128379752 S Bo:1:005:2 -115 31 = 55534243 ad000000 00800000 80010a28 20000000 20000040 00000000 000000 dd65f0e8 4128379808 C Bo:1:005:2 0 31 > * Raw binary format and API |
