linux/kernel/trace/blktrace.c, branch v5.5

cgroup: use cgrp->kn->id as the cgroup ID

2019-11-12T16:18:04Z

cgroup ID is currently allocated using a dedicated per-hierarchy idr and used internally and exposed through tracepoints and bpf. This is confusing because there are tracepoints and other interfaces which use the cgroupfs ino as IDs. The preceding changes made kn->id exposed as ino as 64bit ino on supported archs or ino+gen (low 32bits as ino, high gen). There's no reason for cgroup to use different IDs. The kernfs IDs are unique and userland can easily discover them and map them back to paths using standard file operations. This patch replaces cgroup IDs with kernfs IDs. * cgroup_id() is added and all cgroup ID users are converted to use it. * kernfs_node creation is moved to earlier during cgroup init so that cgroup_id() is available during init. * While at it, s/cgroup/cgrp/ in psi helpers for consistency. * Fallback ID value is changed to 1 to be consistent with root cgroup ID. Signed-off-by: Tejun Heo Reviewed-by: Greg Kroah-Hartman Cc: Namhyung Kim

kernfs: use 64bit inos if ino_t is 64bit

2019-11-12T16:18:04Z

Each kernfs_node is identified with a 64bit ID. The low 32bit is exposed as ino and the high gen. While this already allows using inos as keys by looking up with wildcard generation number of 0, it's adding unnecessary complications for 64bit ino archs which can directly use kernfs_node IDs as inos to uniquely identify each cgroup instance. This patch exposes IDs directly as inos on 64bit ino archs. The conversion is mostly straight-forward. * 32bit ino archs behave the same as before. 64bit ino archs now use the whole 64bit ID as ino and the generation number is fixed at 1. * 64bit inos still use the same idr allocator which gurantees that the lower 32bits identify the current live instance uniquely and the high 32bits are incremented whenever the low bits wrap. As the upper 32bits are no longer used as gen and we don't wanna start ino allocation with 33rd bit set, the initial value for highbits allocation is changed to 0 on 64bit ino archs. * blktrace exposes two 32bit numbers - (INO,GEN) pair - to identify the issuing cgroup. Userland builds FILEID_INO32_GEN fids from these numbers to look up the cgroups. To remain compatible with the behavior, always output (LOW32,HIGH32) which will be constructed back to the original 64bit ID by __kernfs_fh_to_dentry(). Signed-off-by: Tejun Heo Reviewed-by: Greg Kroah-Hartman Cc: Namhyung Kim

kernfs: convert kernfs_node->id from union kernfs_node_id to u64

2019-11-12T16:18:03Z

kernfs_node->id is currently a union kernfs_node_id which represents either a 32bit (ino, gen) pair or u64 value. I can't see much value in the usage of the union - all that's needed is a 64bit ID which the current code is already limited to. Using a union makes the code unnecessarily complicated and prevents using 64bit ino without adding practical benefits. This patch drops union kernfs_node_id and makes kernfs_node->id a u64. ino is stored in the lower 32bits and gen upper. Accessors - kernfs[_id]_ino() and kernfs[_id]_gen() - are added to retrieve the ino and gen. This simplifies ID handling less cumbersome and will allow using 64bit inos on supported archs. This patch doesn't make any functional changes. Signed-off-by: Tejun Heo Reviewed-by: Greg Kroah-Hartman Cc: Namhyung Kim Cc: Jens Axboe Cc: Alexei Starovoitov

blktrace: no need to check return value of debugfs_create functions

2019-06-03T13:39:39Z

When calling debugfs functions, there is no need to ever check the return value. The function can work or not, but the code logic should never do something different based on this. Cc: Jens Axboe Cc: Steven Rostedt Cc: Ingo Molnar Cc: linux-block@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

blkcg: annotate implicit fall through

2019-03-13T20:31:12Z

There is a plan to build the kernel with -Wimplicit-fallthrough and this place in the code produced a warning (W=1). This commit remove the following warning: kernel/trace/blktrace.c:725:9: warning: this statement may fall through [-Wimplicit-fallthrough=] Signed-off-by: Mathieu Malaterre Signed-off-by: Jens Axboe

blkcg: remove bio->bi_css and instead use bio->bi_blkg

2018-12-08T05:26:37Z

Prior patches ensured that any bio that interacts with a request_queue is properly associated with a blkg. This makes bio->bi_css unnecessary as blkg maintains a reference to blkcg already. This removes the bio field bi_css and transfers corresponding uses to access via bi_blkg. Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik Acked-by: Tejun Heo Signed-off-by: Jens Axboe

blkcg: revert blkcg cleanups series

2018-11-02T01:59:53Z

This reverts a series committed earlier due to null pointer exception bug report in [1]. It seems there are edge case interactions that I did not consider and will need some time to understand what causes the adverse interactions. The original series can be found in [2] with a follow up series in [3]. [1] https://www.spinics.net/lists/cgroups/msg20719.html [2] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@gmail.com/ [3] https://lore.kernel.org/lkml/20181020185612.51587-1-dennis@kernel.org/ This reverts the following commits: d459d853c2ed, b2c3fa546705, 101246ec02b5, b3b9f24f5fcc, e2b0989954ae, f0fcb3ec89f3, c839e7a03f92, bdc2491708c4, 74b7c02a9bc1, 5bf9a1f3b4ef, a7b39b4e961c, 07b05bcc3213, 49f4c2dc2b50, 27e6fa996c53 Signed-off-by: Dennis Zhou Signed-off-by: Jens Axboe

blkcg: remove bio->bi_css and instead use bio->bi_blkg

2018-09-22T02:29:13Z

Prior patches ensured that all bios are now associated with some blkg. This now makes bio->bi_css unnecessary as blkg maintains a reference to the blkcg already. This patch removes the field bi_css and transfers corresponding uses to access via bi_blkg. Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik Acked-by: Tejun Heo Signed-off-by: Jens Axboe

Merge tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block

2018-08-22T20:38:05Z

Pull more block updates from Jens Axboe: - Set of bcache fixes and changes (Coly) - The flush warn fix (me) - Small series of BFQ fixes (Paolo) - wbt hang fix (Ming) - blktrace fix (Steven) - blk-mq hardware queue count update fix (Jianchao) - Various little fixes * tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block: (31 commits) block/DAC960.c: make some arrays static const, shrinks object size blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter blk-mq: init hctx sched after update ctx and hctx mapping block: remove duplicate initialization tracing/blktrace: Fix to allow setting same value pktcdvd: fix setting of 'ret' error return for a few cases block: change return type to bool block, bfq: return nbytes and not zero from struct cftype .write() method block, bfq: improve code of bfq_bfqq_charge_time block, bfq: reduce write overcharge block, bfq: always update the budget of an entity when needed block, bfq: readd missing reset of parent-entity service blk-wbt: fix IO hang in wbt_wait() block: don't warn for flush on read-only device bcache: add the missing comments for smp_mb()/smp_wmb() bcache: remove unnecessary space before ioctl function pointer arguments bcache: add missing SPDX header bcache: move open brace at end of function definitions to next line bcache: add static const prefix to char * array declarations bcache: fix code comments style ...

Merge tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2018-08-21T01:32:00Z

Pull tracing updates from Steven Rostedt: - Restructure of lockdep and latency tracers This is the biggest change. Joel Fernandes restructured the hooks from irqs and preemption disabling and enabling. He got rid of a lot of the preprocessor #ifdef mess that they caused. He turned both lockdep and the latency tracers to use trace events inserted in the preempt/irqs disabling paths. But unfortunately, these started to cause issues in corner cases. Thus, parts of the code was reverted back to where lockdep and the latency tracers just get called directly (without using the trace events). But because the original change cleaned up the code very nicely we kept that, as well as the trace events for preempt and irqs disabling, but they are limited to not being called in NMIs. - Have trace events use SRCU for "rcu idle" calls. This was required for the preempt/irqs off trace events. But it also had to not allow them to be called in NMI context. Waiting till Paul makes an NMI safe SRCU API. - New notrace SRCU API to allow trace events to use SRCU. - Addition of mcount-nop option support - SPDX headers replacing GPL templates. - Various other fixes and clean ups. - Some fixes are marked for stable, but were not fully tested before the merge window opened. * tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits) tracing: Fix SPDX format headers to use C++ style comments tracing: Add SPDX License format tags to tracing files tracing: Add SPDX License format to bpf_trace.c blktrace: Add SPDX License format header s390/ftrace: Add -mfentry and -mnop-mcount support tracing: Add -mcount-nop option support tracing: Avoid calling cc-option -mrecord-mcount for every Makefile tracing: Handle CC_FLAGS_FTRACE more accurately Uprobe: Additional argument arch_uprobe to uprobe_write_opcode() Uprobes: Simplify uprobe_register() body tracepoints: Free early tracepoints after RCU is initialized uprobes: Use synchronize_rcu() not synchronize_sched() tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister() ftrace: Remove unused pointer ftrace_swapper_pid tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage" tracing/irqsoff: Handle preempt_count for different configs tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage" tracing: irqsoff: Account for additional preempt_disable trace: Use rcu_dereference_raw for hooks from trace-event subsystem tracing/kprobes: Fix within_notrace_func() to check only notrace functions ...