From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- .../devicetree/bindings/dts-coding-style.rst | 214 +++++++++++++++++++++ 1 file changed, 214 insertions(+) create mode 100644 Documentation/devicetree/bindings/dts-coding-style.rst (limited to 'Documentation/devicetree/bindings/dts-coding-style.rst') diff --git a/Documentation/devicetree/bindings/dts-coding-style.rst b/Documentation/devicetree/bindings/dts-coding-style.rst new file mode 100644 index 000000000..63648db37 --- /dev/null +++ b/Documentation/devicetree/bindings/dts-coding-style.rst @@ -0,0 +1,214 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================================== +Devicetree Sources (DTS) Coding Style +===================================== + +When writing Devicetree Sources (DTS) please observe below guidelines. They +should be considered complementary to any rules expressed already in +the Devicetree Specification and the dtc compiler (including W=1 and W=2 +builds). + +Individual architectures and subarchitectures can define additional rules, +making the coding style stricter. + +Naming and Valid Characters +--------------------------- + +The Devicetree Specification allows a broad range of characters in node +and property names, but this coding style narrows the range down to achieve +better code readability. + +1. Node and property names can use only the following characters: + + * Lowercase characters: [a-z] + * Digits: [0-9] + * Dash: - + +2. Labels can use only the following characters: + + * Lowercase characters: [a-z] + * Digits: [0-9] + * Underscore: _ + +3. Unless a bus defines differently, unit addresses shall use lowercase + hexadecimal digits, without leading zeros (padding). + +4. Hex values in properties, e.g. "reg", shall use lowercase hex. The address + part can be padded with leading zeros. + +Example:: + + gpi_dma2: dma-controller@a00000 { + compatible = "qcom,sm8550-gpi-dma", "qcom,sm6350-gpi-dma"; + reg = <0x0 0x00a00000 0x0 0x60000>; + } + +Order of Nodes +-------------- + +1. Nodes on any bus, thus using unit addresses for children, shall be + ordered by unit address in ascending order. + Alternatively for some subarchitectures, nodes of the same type can be + grouped together, e.g. all I2C controllers one after another even if this + breaks unit address ordering. + +2. Nodes without unit addresses shall be ordered alpha-numerically by the node + name. For a few node types, they can be ordered by the main property, e.g. + pin configuration states ordered by value of "pins" property. + +3. When extending nodes in the board DTS via &label, the entries shall be + ordered either alpha-numerically or by keeping the order from DTSI, where + the choice depends on the subarchitecture. + +The above-described ordering rules are easy to enforce during review, reduce +chances of conflicts for simultaneous additions of new nodes to a file and help +in navigating through the DTS source. + +Example:: + + /* SoC DTSI */ + + / { + cpus { + /* ... */ + }; + + psci { + /* ... */ + }; + + soc@0 { + dma: dma-controller@10000 { + /* ... */ + }; + + clk: clock-controller@80000 { + /* ... */ + }; + }; + }; + + /* Board DTS - alphabetical order */ + + &clk { + /* ... */ + }; + + &dma { + /* ... */ + }; + + /* Board DTS - alternative order, keep as DTSI */ + + &dma { + /* ... */ + }; + + &clk { + /* ... */ + }; + +Order of Properties in Device Node +---------------------------------- + +The following order of properties in device nodes is preferred: + +1. "device_type" (if applicable) +2. "compatible" +3. "reg" +4. "ranges" +5. Standard/common properties (defined by common bindings, e.g. without + vendor-prefixes) +6. Vendor-specific properties +7. "status" (if applicable), preceded by a blank line if there is content + before the property +8. Child nodes, where each node is preceded with a blank line + +The "status" property is by default "okay", thus it can be omitted. + +The above-described ordering follows this approach: + +1. Most important properties start the node: compatible then bus addressing to + match unit address. +2. Each node will have common properties in similar place. +3. Status is the last information to annotate that device node is or is not + finished (board resources are needed). + +The individual properties inside each group shall use natural sort order by +the property name. + +Example:: + + /* SoC DTSI */ + + device_node: device-class@6789abc { + compatible = "vendor,device"; + reg = <0x0 0x06789abc 0x0 0xa123>; + ranges = <0x0 0x0 0x06789abc 0x1000>; + #dma-cells = <1>; + clocks = <&clock_controller 0>, <&clock_controller 1>; + clock-names = "bus", "host"; + #address-cells = <1>; + #size-cells = <1>; + vendor,custom-property = <2>; + + status = "disabled"; + + child_node: child-class@100 { + reg = <0x100 0x200>; + /* ... */ + }; + }; + + /* Board DTS */ + + &device_node { + vdd-0v9-supply = <&board_vreg1>; + vdd-1v8-supply = <&board_vreg4>; + vdd-3v3-supply = <&board_vreg2>; + vdd-12v-supply = <&board_vreg3>; + + status = "okay"; + } + +Indentation and wrapping +------------------------ + +1. Use indentation and wrap lines according to + Documentation/process/coding-style.rst. +2. Each entry in arrays with multiple cells, e.g. "reg" with two IO addresses, + shall be enclosed in <>. +3. For arrays spanning across lines, it is preferred to split on item boundary + and align the continued entries with opening < from the first line. + Usually avoid splitting individual items unless they significantly exceed + line wrap limit. + +Example:: + + thermal-sensor@c271000 { + compatible = "qcom,sm8550-tsens", "qcom,tsens-v2"; + reg = <0x0 0x0c271000 0x0 0x1000>, + <0x0 0x0c222000 0x0 0x1000>; + /* Lines exceeding coding style line wrap limit: */ + interconnects = <&aggre1_noc MASTER_USB3_0 0 &mc_virt SLAVE_EBI1 0>, + <&gem_noc MASTER_APPSS_PROC 0 &config_noc SLAVE_USB3_0 0>; + }; + +Organizing DTSI and DTS +----------------------- + +The DTSI and DTS files shall be organized in a way representing the common, +reusable parts of hardware. Typically, this means organizing DTSI and DTS files +into several files: + +1. DTSI with contents of the entire SoC, without nodes for hardware not present + on the SoC. +2. If applicable: DTSI with common or re-usable parts of the hardware, e.g. + entire System-on-Module. +3. DTS representing the board. + +Hardware components that are present on the board shall be placed in the +board DTS, not in the SoC or SoM DTSI. A partial exception is a common +external reference SoC input clock, which could be coded as a fixed-clock in +the SoC DTSI with its frequency provided by each board DTS. -- cgit v1.3.1