diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DMA-API.txt | 69 | ||||
| -rw-r--r-- | Documentation/DMA-attributes.txt | 24 | ||||
| -rw-r--r-- | Documentation/cgroups.txt | 3 | ||||
| -rw-r--r-- | Documentation/controllers/devices.txt | 48 | ||||
| -rw-r--r-- | Documentation/controllers/resource_counter.txt | 181 | ||||
| -rw-r--r-- | Documentation/cpu-freq/user-guide.txt | 14 | ||||
| -rw-r--r-- | Documentation/cpusets.txt | 26 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 10 | ||||
| -rw-r--r-- | Documentation/keys-request-key.txt | 11 | ||||
| -rw-r--r-- | Documentation/keys.txt | 59 | ||||
| -rw-r--r-- | Documentation/oops-tracing.txt | 4 | ||||
| -rw-r--r-- | Documentation/sysrq.txt | 2 |
12 files changed, 423 insertions, 28 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index b939ebb62871..80d150458c80 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -145,7 +145,7 @@ Part Ic - DMA addressing limitations int dma_supported(struct device *dev, u64 mask) int -pci_dma_supported(struct device *dev, u64 mask) +pci_dma_supported(struct pci_dev *hwdev, u64 mask) Checks to see if the device can support DMA to the memory described by mask. @@ -189,7 +189,7 @@ dma_addr_t dma_map_single(struct device *dev, void *cpu_addr, size_t size, enum dma_data_direction direction) dma_addr_t -pci_map_single(struct device *dev, void *cpu_addr, size_t size, +pci_map_single(struct pci_dev *hwdev, void *cpu_addr, size_t size, int direction) Maps a piece of processor virtual memory so it can be accessed by the @@ -395,6 +395,71 @@ Notes: You must do this: See also dma_map_single(). +dma_addr_t +dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size, + enum dma_data_direction dir, + struct dma_attrs *attrs) + +void +dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr, + size_t size, enum dma_data_direction dir, + struct dma_attrs *attrs) + +int +dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl, + int nents, enum dma_data_direction dir, + struct dma_attrs *attrs) + +void +dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl, + int nents, enum dma_data_direction dir, + struct dma_attrs *attrs) + +The four functions above are just like the counterpart functions +without the _attrs suffixes, except that they pass an optional +struct dma_attrs*. + +struct dma_attrs encapsulates a set of "dma attributes". For the +definition of struct dma_attrs see linux/dma-attrs.h. + +The interpretation of dma attributes is architecture-specific, and +each attribute should be documented in Documentation/DMA-attributes.txt. + +If struct dma_attrs* is NULL, the semantics of each of these +functions is identical to those of the corresponding function +without the _attrs suffix. As a result dma_map_single_attrs() +can generally replace dma_map_single(), etc. + +As an example of the use of the *_attrs functions, here's how +you could pass an attribute DMA_ATTR_FOO when mapping memory +for DMA: + +#include <linux/dma-attrs.h> +/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and + * documented in Documentation/DMA-attributes.txt */ +... + + DEFINE_DMA_ATTRS(attrs); + dma_set_attr(DMA_ATTR_FOO, &attrs); + .... + n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr); + .... + +Architectures that care about DMA_ATTR_FOO would check for its +presence in their implementations of the mapping and unmapping +routines, e.g.: + +void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr, + size_t size, enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + .... + int foo = dma_get_attr(DMA_ATTR_FOO, attrs); + .... + if (foo) + /* twizzle the frobnozzle */ + .... + Part II - Advanced dma_ usage ----------------------------- diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt new file mode 100644 index 000000000000..6d772f84b477 --- /dev/null +++ b/Documentation/DMA-attributes.txt @@ -0,0 +1,24 @@ + DMA attributes + ============== + +This document describes the semantics of the DMA attributes that are +defined in linux/dma-attrs.h. + +DMA_ATTR_WRITE_BARRIER +---------------------- + +DMA_ATTR_WRITE_BARRIER is a (write) barrier attribute for DMA. DMA +to a memory region with the DMA_ATTR_WRITE_BARRIER attribute forces +all pending DMA writes to complete, and thus provides a mechanism to +strictly order DMA from a device across all intervening busses and +bridges. This barrier is not specific to a particular type of +interconnect, it applies to the system as a whole, and so its +implementation must account for the idiosyncracies of the system all +the way from the DMA device to memory. + +As an example of a situation where DMA_ATTR_WRITE_BARRIER would be +useful, suppose that a device does a DMA write to indicate that data is +ready and available in memory. The DMA of the "completion indication" +could race with data DMA. Mapping the memory used for completion +indications with DMA_ATTR_WRITE_BARRIER would prevent the race. + diff --git a/Documentation/cgroups.txt b/Documentation/cgroups.txt index 31d12e21ff8a..c298a6690e0d 100644 --- a/Documentation/cgroups.txt +++ b/Documentation/cgroups.txt @@ -500,8 +500,7 @@ post-attachment activity that requires memory allocations or blocking. void fork(struct cgroup_subsy *ss, struct task_struct *task) -Called when a task is forked into a cgroup. Also called during -registration for all existing tasks. +Called when a task is forked into a cgroup. void exit(struct cgroup_subsys *ss, struct task_struct *task) diff --git a/Documentation/controllers/devices.txt b/Documentation/controllers/devices.txt new file mode 100644 index 000000000000..4dcea42432c2 --- /dev/null +++ b/Documentation/controllers/devices.txt @@ -0,0 +1,48 @@ +Device Whitelist Controller + +1. Description: + +Implement a cgroup to track and enforce open and mknod restrictions +on device files. A device cgroup associates a device access +whitelist with each cgroup. A whitelist entry has 4 fields. +'type' is a (all), c (char), or b (block). 'all' means it applies +to all types and all major and minor numbers. Major and minor are +either an integer or * for all. Access is a composition of r +(read), w (write), and m (mknod). + +The root device cgroup starts with rwm to 'all'. A child device +cgroup gets a copy of the parent. Administrators can then remove +devices from the whitelist or add new entries. A child cgroup can +never receive a device access which is denied its parent. However +when a device access is removed from a parent it will not also be +removed from the child(ren). + +2. User Interface + +An entry is added using devices.allow, and removed using +devices.deny. For instance + + echo 'c 1:3 mr' > /cgroups/1/devices.allow + +allows cgroup 1 to read and mknod the device usually known as +/dev/null. Doing + + echo a > /cgroups/1/devices.deny + +will remove the default 'a *:* mrw' entry. + +3. Security + +Any task can move itself between cgroups. This clearly won't +suffice, but we can decide the best way to adequately restrict +movement as people get some experience with this. We may just want +to require CAP_SYS_ADMIN, which at least is a separate bit from +CAP_MKNOD. We may want to just refuse moving to a cgroup which +isn't a descendent of the current one. Or we may want to use +CAP_MAC_ADMIN, since we really are trying to lock down root. + +CAP_SYS_ADMIN is needed to modify the whitelist or move another +task to a new cgroup. (Again we'll probably want to change that). + +A cgroup may not be granted more permissions than the cgroup's +parent has. diff --git a/Documentation/controllers/resource_counter.txt b/Documentation/controllers/resource_counter.txt new file mode 100644 index 000000000000..f196ac1d7d25 --- /dev/null +++ b/Documentation/controllers/resource_counter.txt @@ -0,0 +1,181 @@ + + The Resource Counter + +The resource counter, declared at include/linux/res_counter.h, +is supposed to facilitate the resource management by controllers +by providing common stuff for accounting. + +This "stuff" includes the res_counter structure and routines +to work with it. + + + +1. Crucial parts of the res_counter structure + + a. unsigned long long usage + + The usage value shows the amount of a resource that is consumed + by a group at a given time. The units of measurement should be + determined by the controller that uses this counter. E.g. it can + be bytes, items or any other unit the controller operates on. + + b. unsigned long long max_usage + + The maximal value of the usage over time. + + This value is useful when gathering statistical information about + the particular group, as it shows the actual resource requirements + for a particular group, not just some usage snapshot. + + c. unsigned long long limit + + The maximal allowed amount of resource to consume by the group. In + case the group requests for more resources, so that the usage value + would exceed the limit, the resource allocation is rejected (see + the next section). + + d. unsigned long long failcnt + + The failcnt stands for "failures counter". This is the number of + resource allocation attempts that failed. + + c. spinlock_t lock + + Protects changes of the above values. + + + +2. Basic accounting routines + + a. void res_counter_init(struct res_counter *rc) + + Initializes the resource counter. As usual, should be the first + routine called for a new counter. + + b. int res_counter_charge[_locked] + (struct res_counter *rc, unsigned long val) + + When a resource is about to be allocated it has to be accounted + with the appropriate resource counter (controller should determine + which one to use on its own). This operation is called "charging". + + This is not very important which operation - resource allocation + or charging - is performed first, but + * if the allocation is performed first, this may create a + temporary resource over-usage by the time resource counter is + charged; + * if the charging is performed first, then it should be uncharged + on error path (if the one is called). + + c. void res_counter_uncharge[_locked] + (struct res_counter *rc, unsigned long val) + + When a resource is released (freed) it should be de-accounted + from the resource counter it was accounted to. This is called + "uncharging". + + The _locked routines imply that the res_counter->lock is taken. + + + 2.1 Other accounting routines + + There are more routines that may help you with common needs, like + checking whether the limit is reached or resetting the max_usage + value. They are all declared in include/linux/res_counter.h. + + + +3. Analyzing the resource counter registrations + + a. If the failcnt value constantly grows, this means that the counter's + limit is too tight. Either the group is misbehaving and consumes too + many resources, or the configuration is not suitable for the group + and the limit should be increased. + + b. The max_usage value can be used to quickly tune the group. One may + set the limits to maximal values and either load the container with + a common pattern or leave one for a while. After this the max_usage + value shows the amount of memory the container would require during + its common activity. + + Setting the limit a bit above this value gives a pretty good + configuration that works in most of the cases. + + c. If the max_usage is much less than the limit, but the failcnt value + is growing, then the group tries to allocate a big chunk of resource + at once. + + d. If the max_usage is much less than the limit, but the failcnt value + is 0, then this group is given too high limit, that it does not + require. It is better to lower the limit a bit leaving more resource + for other groups. + + + +4. Communication with the control groups subsystem (cgroups) + +All the resource controllers that are using cgroups and resource counters +should provide files (in the cgroup filesystem) to work with the resource +counter fields. They are recommended to adhere to the following rules: + + a. File names + + Field name File name + --------------------------------------------------- + usage usage_in_<unit_of_measurement> + max_usage max_usage_in_<unit_of_measurement> + limit limit_in_<unit_of_measurement> + failcnt failcnt + lock no file :) + + b. Reading from file should show the corresponding field value in the + appropriate format. + + c. Writing to file + + Field Expected behavior + ---------------------------------- + usage prohibited + max_usage reset to usage + limit set the limit + failcnt reset to zero + + + +5. Usage example + + a. Declare a task group (take a look at cgroups subsystem for this) and + fold a res_counter into it + + struct my_group { + struct res_counter res; + + <other fields> + } + + b. Put hooks in resource allocation/release paths + + int alloc_something(...) + { + if (res_counter_charge(res_counter_ptr, amount) < 0) + return -ENOMEM; + + <allocate the resource and return to the caller> + } + + void release_something(...) + { + res_counter_uncharge(res_counter_ptr, amount); + + <release the resource> + } + + In order to keep the usage value self-consistent, both the + "res_counter_ptr" and the "amount" in release_something() should be + the same as they were in the alloc_something() when the releasing + resource was allocated. + + c. Provide the way to read res_counter values and set them (the cgroups + still can help with it). + + c. Compile and run :) diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt index af3b925ece08..6c442d8426b5 100644 --- a/Documentation/cpu-freq/user-guide.txt +++ b/Documentation/cpu-freq/user-guide.txt @@ -154,6 +154,11 @@ scaling_governor, and by "echoing" the name of another that some governors won't load - they only work on some specific architectures or processors. + +cpuinfo_cur_freq : Current speed of the CPU, in KHz. + +scaling_available_frequencies : List of available frequencies, in KHz. + scaling_min_freq and scaling_max_freq show the current "policy limits" (in kHz). By echoing new values into these @@ -162,6 +167,15 @@ scaling_max_freq show the current "policy limits" (in first set scaling_max_freq, then scaling_min_freq. +affected_cpus : List of CPUs that require software coordination + of frequency. + +related_cpus : List of CPUs that need some sort of frequency + coordination, whether software or hardware. + +scaling_driver : Hardware driver for cpufreq. + +scaling_cur_freq : Current frequency of the CPU, in KHz. If you have selected the "userspace" governor which allows you to set the CPU operating frequency to a specific value, you can read out diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt index aa854b9b18cd..fb7b361e6eea 100644 --- a/Documentation/cpusets.txt +++ b/Documentation/cpusets.txt @@ -171,6 +171,7 @@ files describing that cpuset: - memory_migrate flag: if set, move pages to cpusets nodes - cpu_exclusive flag: is cpu placement exclusive? - mem_exclusive flag: is memory placement exclusive? + - mem_hardwall flag: is memory allocation hardwalled - memory_pressure: measure of how much paging pressure in cpuset In addition, the root cpuset only has the following file: @@ -222,17 +223,18 @@ If a cpuset is cpu or mem exclusive, no other cpuset, other than a direct ancestor or descendent, may share any of the same CPUs or Memory Nodes. -A cpuset that is mem_exclusive restricts kernel allocations for -page, buffer and other data commonly shared by the kernel across -multiple users. All cpusets, whether mem_exclusive or not, restrict -allocations of memory for user space. This enables configuring a -system so that several independent jobs can share common kernel data, -such as file system pages, while isolating each jobs user allocation in -its own cpuset. To do this, construct a large mem_exclusive cpuset to -hold all the jobs, and construct child, non-mem_exclusive cpusets for -each individual job. Only a small amount of typical kernel memory, -such as requests from interrupt handlers, is allowed to be taken -outside even a mem_exclusive cpuset. +A cpuset that is mem_exclusive *or* mem_hardwall is "hardwalled", +i.e. it restricts kernel allocations for page, buffer and other data +commonly shared by the kernel across multiple users. All cpusets, +whether hardwalled or not, restrict allocations of memory for user +space. This enables configuring a system so that several independent +jobs can share common kernel data, such as file system pages, while +isolating each job's user allocation in its own cpuset. To do this, +construct a large mem_exclusive cpuset to hold all the jobs, and +construct child, non-mem_exclusive cpusets for each individual job. +Only a small amount of typical kernel memory, such as requests from +interrupt handlers, is allowed to be taken outside even a +mem_exclusive cpuset. 1.5 What is memory_pressure ? @@ -707,7 +709,7 @@ Now you want to do something with this cpuset. In this directory you can find several files: # ls -cpus cpu_exclusive mems mem_exclusive tasks +cpus cpu_exclusive mems mem_exclusive mem_hardwall tasks Reading them will give you information about the state of this cpuset: the CPUs and Memory Nodes it can use, the processes that are using diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index e5f3d918316f..3ce193f86565 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -627,8 +627,7 @@ and is between 256 and 4096 characters. It is defined in the file eata= [HW,SCSI] edd= [EDD] - Format: {"of[f]" | "sk[ipmbr]"} - See comment in arch/i386/boot/edd.S + Format: {"off" | "on" | "skip[mbr]"} eisa_irq_edge= [PARISC,HW] See header of drivers/parisc/eisa.c. @@ -1389,6 +1388,13 @@ and is between 256 and 4096 characters. It is defined in the file nr_uarts= [SERIAL] maximum number of UARTs to be registered. + olpc_ec_timeout= [OLPC] ms delay when issuing EC commands + Rather than timing out after 20 ms if an EC + command is not properly ACKed, override the length + of the timeout. We have interrupts disabled while + waiting for the ACK, so if this is set too high + interrupts *may* be lost! + opl3= [HW,OSS] Format: <io> diff --git a/Documentation/keys-request-key.txt b/Documentation/keys-request-key.txt index 266955d23ee6..09b55e461740 100644 --- a/Documentation/keys-request-key.txt +++ b/Documentation/keys-request-key.txt @@ -11,26 +11,29 @@ request_key*(): struct key *request_key(const struct key_type *type, const char *description, - const char *callout_string); + const char *callout_info); or: struct key *request_key_with_auxdata(const struct key_type *type, const char *description, - const char *callout_string, + const char *callout_info, + size_t callout_len, void *aux); or: struct key *request_key_async(const struct key_type *type, const char *description, - const char *callout_string); + const char *callout_info, + size_t callout_len); or: struct key *request_key_async_with_auxdata(const struct key_type *type, const char *description, - const char *callout_string, + const char *callout_info, + size_t callout_len, void *aux); Or by userspace invoking the request_key system call: diff --git a/Documentation/keys.txt b/Documentation/keys.txt index 51652d39e61c..d5c7a57d1700 100644 --- a/Documentation/keys.txt +++ b/Documentation/keys.txt @@ -170,7 +170,8 @@ The key service provides a number of features besides keys: amount of description and payload space that can be consumed. The user can view information on this and other statistics through procfs - files. + files. The root user may also alter the quota limits through sysctl files + (see the section "New procfs files"). Process-specific and thread-specific keyrings are not counted towards a user's quota. @@ -329,6 +330,27 @@ about the status of the key service: <bytes>/<max> Key size quota +Four new sysctl files have been added also for the purpose of controlling the +quota limits on keys: + + (*) /proc/sys/kernel/keys/root_maxkeys + /proc/sys/kernel/keys/root_maxbytes + + These files hold the maximum number of keys that root may have and the + maximum total number of bytes of data that root may have stored in those + keys. + + (*) /proc/sys/kernel/keys/maxkeys + /proc/sys/kernel/keys/maxbytes + + These files hold the maximum number of keys that each non-root user may + have and the maximum total number of bytes of data that each of those + users may have stored in their keys. + +Root may alter these by writing each new limit as a decimal number string to +the appropriate file. + + =============================== USERSPACE SYSTEM CALL INTERFACE =============================== @@ -711,6 +733,27 @@ The keyctl syscall functions are: The assumed authoritative key is inherited across fork and exec. + (*) Get the LSM security context attached to a key. + + long keyctl(KEYCTL_GET_SECURITY, key_serial_t key, char *buffer, + size_t buflen) + + This function returns a string that represents the LSM security context + attached to a key in the buffer provided. + + Unless there's an error, it always returns the amount of data it could + produce, even if that's too big for the buffer, but it won't copy more + than requested to userspace. If the buffer pointer is NULL then no copy + will take place. + + A NUL character is included at the end of the string if the buffer is + sufficiently big. This is included in the returned count. If no LSM is + in force then an empty string will be returned. + + A process must have view permission on the key for this function to be + successful. + + =============== KERNEL SERVICES =============== @@ -771,7 +814,7 @@ payload contents" for more information. struct key *request_key(const struct key_type *type, const char *description, - const char *callout_string); + const char *callout_info); This is used to request a key or keyring with a description that matches the description specified according to the key type's match function. This @@ -793,24 +836,28 @@ payload contents" for more information. struct key *request_key_with_auxdata(const struct key_type *type, const char *description, - const char *callout_string, + const void *callout_info, + size_t callout_len, void *aux); This is identical to request_key(), except that the auxiliary data is - passed to the key_type->request_key() op if it exists. + passed to the key_type->request_key() op if it exists, and the callout_info + is a blob of length callout_len, if given (the length may be 0). (*) A key can be requested asynchronously by calling one of: struct key *request_key_async(const struct key_type *type, const char *description, - const char *callout_string); + const void *callout_info, + size_t callout_len); or: struct key *request_key_async_with_auxdata(const struct key_type *type, const char *description, - const char *callout_string, + const char *callout_info, + size_t callout_len, void *aux); which are asynchronous equivalents of request_key() and diff --git a/Documentation/oops-tracing.txt b/Documentation/oops-tracing.txt index 7f60dfe642ca..b152e81da592 100644 --- a/Documentation/oops-tracing.txt +++ b/Documentation/oops-tracing.txt @@ -253,6 +253,10 @@ characters, each representing a particular tainted value. 8: 'D' if the kernel has died recently, i.e. there was an OOPS or BUG. + 9: 'A' if the ACPI table has been overridden. + + 10: 'W' if a warning has previously been issued by the kernel. + The primary reason for the 'Tainted: ' string is to tell kernel debuggers if this is a clean kernel or if anything unusual has occurred. Tainting is permanent: even if an offending module is diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt index 10c8f6922ef4..5ce0952aa065 100644 --- a/Documentation/sysrq.txt +++ b/Documentation/sysrq.txt @@ -85,6 +85,8 @@ On all - write a character to /proc/sysrq-trigger. e.g.: 'k' - Secure Access Key (SAK) Kills all programs on the current virtual console. NOTE: See important comments below in SAK section. +'l' - Shows a stack backtrace for all active CPUs. + 'm' - Will dump current memory info to your console. 'n' - Used to make RT tasks nice-able |