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 --- Documentation/ABI/testing/sysfs-class-devfreq | 143 ++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-devfreq (limited to 'Documentation/ABI/testing/sysfs-class-devfreq') diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq new file mode 100644 index 000000000..df8ba88b9 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-devfreq @@ -0,0 +1,143 @@ +What: /sys/class/devfreq/.../ +Date: September 2011 +Contact: MyungJoo Ham +Description: + Provide a place in sysfs for the devfreq objects. + This allows accessing various devfreq specific variables. + The name of devfreq object denoted as ... is same as the + name of device using devfreq. + +What: /sys/class/devfreq/.../name +Date: November 2019 +Contact: Chanwoo Choi +Description: + The /sys/class/devfreq/.../name shows the name of device + of the corresponding devfreq object. + +What: /sys/class/devfreq/.../governor +Date: September 2011 +Contact: MyungJoo Ham +Description: + The /sys/class/devfreq/.../governor show or set the name of the + governor used by the corresponding devfreq object. + +What: /sys/class/devfreq/.../cur_freq +Date: September 2011 +Contact: MyungJoo Ham +Description: + The /sys/class/devfreq/.../cur_freq shows the current + frequency of the corresponding devfreq object. Same as + target_freq when get_cur_freq() is not implemented by + devfreq driver. + +What: /sys/class/devfreq/.../target_freq +Date: September 2012 +Contact: Rajagopal Venkat +Description: + The /sys/class/devfreq/.../target_freq shows the next governor + predicted target frequency of the corresponding devfreq object. + +What: /sys/class/devfreq/.../trans_stat +Date: October 2012 +Contact: MyungJoo Ham +Description: + This ABI shows or clears the statistics of devfreq behavior + on a specific device. It shows the time spent in each state + and the number of transitions between states. + In order to activate this ABI, the devfreq target device + driver should provide the list of available frequencies + with its profile. If need to reset the statistics of devfreq + behavior on a specific device, enter 0(zero) to 'trans_stat' + as following:: + + echo 0 > /sys/class/devfreq/.../trans_stat + + If the transition table is bigger than PAGE_SIZE, reading + this will return an -EFBIG error. + +What: /sys/class/devfreq/.../available_frequencies +Date: October 2012 +Contact: Nishanth Menon +Description: + The /sys/class/devfreq/.../available_frequencies shows + the available frequencies of the corresponding devfreq object. + This is a snapshot of available frequencies and not limited + by the min/max frequency restrictions. + +What: /sys/class/devfreq/.../available_governors +Date: October 2012 +Contact: Nishanth Menon +Description: + The /sys/class/devfreq/.../available_governors shows + currently available governors in the system. + +What: /sys/class/devfreq/.../min_freq +Date: January 2013 +Contact: MyungJoo Ham +Description: + The /sys/class/devfreq/.../min_freq shows and stores + the minimum frequency requested by users. It is 0 if + the user does not care. min_freq overrides the + frequency requested by governors. + +What: /sys/class/devfreq/.../max_freq +Date: January 2013 +Contact: MyungJoo Ham +Description: + The /sys/class/devfreq/.../max_freq shows and stores + the maximum frequency requested by users. It is 0 if + the user does not care. max_freq overrides the + frequency requested by governors and min_freq. + The max_freq overrides min_freq because max_freq may be + used to throttle devices to avoid overheating. + +What: /sys/class/devfreq/.../polling_interval +Date: September 2011 +Contact: MyungJoo Ham +Description: + The /sys/class/devfreq/.../polling_interval shows and sets + the requested polling interval of the corresponding devfreq + object. The values are represented in ms. If the value is + less than 1 jiffy, it is considered to be 0, which means + no polling. This value is meaningless if the governor is + not polling. + + A list of governors that support the node: + - simple_ondmenad + - tegra_actmon + +What: /sys/class/devfreq/.../userspace/set_freq +Date: September 2011 +Contact: MyungJoo Ham +Description: + The /sys/class/devfreq/.../userspace/set_freq shows and + sets the requested frequency for the devfreq object if + userspace governor is in effect. + + A list of governors that support the node: + - userspace + +What: /sys/class/devfreq/.../timer +Date: July 2020 +Contact: Chanwoo Choi +Description: + This ABI shows and stores the kind of work timer by users. + This work timer is used by devfreq workqueue in order to + monitor the device status such as utilization. The user + can change the work timer on runtime according to their demand + as following:: + + echo deferrable > /sys/class/devfreq/.../timer + echo delayed > /sys/class/devfreq/.../timer + + A list of governors that support the node: + - simple_ondemand + +What: /sys/class/devfreq/.../related_cpus +Date: June 2025 +Contact: Linux power management list +Description: The list of CPUs whose performance is closely related to the + frequency of this devfreq domain. + + This file is only present if a specific devfreq device is + closely associated with a subset of CPUs. -- cgit v1.3.1