linux/kernel/trace/blktrace.c, branch v6.14

blktrace: remove redundant return at end of function

2024-12-23T15:17:23Z

A recent change added return 0 before an existing return statement at the end of function blk_trace_setup. The final return is now redundant, so remove it. Fixes: 64d124798244 ("blktrace: move copy_[to|from]_user() out of ->debugfs_lock") Signed-off-by: Colin Ian King Link: https://lore.kernel.org/r/20241204150450.399005-1-colin.i.king@gmail.com Signed-off-by: Jens Axboe

blktrace: move copy_[to|from]_user() out of ->debugfs_lock

2024-12-23T15:17:22Z

Move copy_[to|from]_user() out of ->debugfs_lock and cut the dependency between mm->mmap_lock and q->debugfs_lock, then we avoids lots of lockdep false positive warning. Obviously ->debug_lock isn't needed for copy_[to|from]_user(). The only behavior change is to call blk_trace_remove() in case of setup failure handling by re-grabbing ->debugfs_lock, and this way is just fine since we do cover concurrent setup() & remove(). Reported-by: syzbot+91585b36b538053343e4@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-block/67450fd4.050a0220.1286eb.0007.GAE@google.com/ Closes: https://lore.kernel.org/linux-block/6742e584.050a0220.1cc393.0038.GAE@google.com/ Closes: https://lore.kernel.org/linux-block/6742a600.050a0220.1cc393.002e.GAE@google.com/ Closes: https://lore.kernel.org/linux-block/67420102.050a0220.1cc393.0019.GAE@google.com/ Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20241128125029.4152292-3-ming.lei@redhat.com Signed-off-by: Jens Axboe

blktrace: don't centralize grabbing q->debugfs_mutex in blk_trace_ioctl

2024-12-23T15:17:22Z

Call each handler directly and the handler do grab q->debugfs_mutex, prepare for killing dependency between ->debug_mutex and ->mmap_lock. Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20241128125029.4152292-2-ming.lei@redhat.com Signed-off-by: Jens Axboe

blktrace: convert strncpy() to strscpy_pad()

2024-04-26T04:07:08Z

gcc-9 warns about a possibly non-terminated string copy: kernel/trace/blktrace.c: In function 'do_blk_trace_setup': kernel/trace/blktrace.c:527:2: error: 'strncpy' specified bound 32 equals destination size [-Werror=stringop-truncation] Newer versions are fine here because they see the following explicit nul-termination. Using strscpy_pad() avoids the warning and simplifies the code a little. The padding helps give a clean buffer to userspace. Link: https://lkml.kernel.org/r/20240409140059.3806717-5-arnd@kernel.org Signed-off-by: Arnd Bergmann Acked-by: Justin Stitt Cc: Alexey Starikovskiy Cc: Bob Moore Cc: Jens Axboe Cc: Len Brown Cc: Lin Ming Cc: Masahiro Yamada Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Nathan Chancellor Cc: Nicolas Schier Cc: Rafael J. Wysocki Cc: "Richard Russon (FlatCap)" Cc: Steven Rostedt Signed-off-by: Andrew Morton

block: remove more NULL checks after bdev_get_queue()

2023-02-21T16:23:22Z

bdev_get_queue() never returns NULL. Several commits [1][2] have been made before to remove such superfluous checks, but some still remained. For places where bdev_get_queue() is called solely for NULL checks, it is removed entirely. [1] commit ec9fd2a13d74 ("blk-lib: don't check bdev_get_queue() NULL check") [2] commit fea127b36c93 ("block: remove superfluous check for request queue in bdev_is_zoned()") Signed-off-by: Juhyung Park Reviewed-by: Pankaj Raghav Link: https://lore.kernel.org/r/20230203024029.48260-1-qkrwngud825@gmail.com Signed-off-by: Jens Axboe

trace/blktrace: fix memory leak with using debugfs_lookup()

2023-02-06T16:29:30Z

When calling debugfs_lookup() the result must have dput() called on it, otherwise the memory will leak over time. To make things simpler, just call debugfs_lookup_and_remove() instead which handles all of the logic at once. Cc: Jens Axboe Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-trace-kernel@vger.kernel.org Signed-off-by: Greg Kroah-Hartman Reviewed-by: Bart Van Assche Link: https://lore.kernel.org/r/20230202141956.2299521-1-gregkh@linuxfoundation.org Signed-off-by: Jens Axboe

blktrace: Fix output non-blktrace event when blk_classic option enabled

2022-12-08T16:26:11Z

When the blk_classic option is enabled, non-blktrace events must be filtered out. Otherwise, events of other types are output in the blktrace classic format, which is unexpected. The problem can be triggered in the following ways: # echo 1 > /sys/kernel/debug/tracing/options/blk_classic # echo 1 > /sys/kernel/debug/tracing/events/enable # echo blk > /sys/kernel/debug/tracing/current_tracer # cat /sys/kernel/debug/tracing/trace_pipe Fixes: c71a89615411 ("blktrace: add ftrace plugin") Signed-off-by: Yang Jihong Link: https://lore.kernel.org/r/20221122040410.85113-1-yangjihong1@huawei.com Signed-off-by: Jens Axboe

block: bdev & blktrace: use consistent function doc. notation

2022-12-01T16:16:46Z

Use only one hyphen in kernel-doc notation between the function name and its short description. The is the documented kerenl-doc format. It also fixes the HTML presentation to be consistent with other functions. Signed-off-by: Randy Dunlap Cc: Jens Axboe Cc: linux-block@vger.kernel.org Link: https://lore.kernel.org/r/20221201070331.25685-1-rdunlap@infradead.org Signed-off-by: Jens Axboe

blktrace: remove unnessary stop block trace in 'blk_trace_shutdown'

2022-10-20T13:02:52Z

As previous commit, 'blk_trace_cleanup' will stop block trace if block trace's state is 'Blktrace_running'. So remove unnessary stop block trace in 'blk_trace_shutdown'. Signed-off-by: Ye Bin Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20221019033602.752383-4-yebin@huaweicloud.com Signed-off-by: Jens Axboe

blktrace: fix possible memleak in '__blk_trace_remove'

2022-10-20T13:02:52Z

When test as follows: step1: ioctl(sda, BLKTRACESETUP, &arg) step2: ioctl(sda, BLKTRACESTART, NULL) step3: ioctl(sda, BLKTRACETEARDOWN, NULL) step4: ioctl(sda, BLKTRACESETUP, &arg) Got issue as follows: debugfs: File 'dropped' in directory 'sda' already present! debugfs: File 'msg' in directory 'sda' already present! debugfs: File 'trace0' in directory 'sda' already present! And also find syzkaller report issue like "KASAN: use-after-free Read in relay_switch_subbuf" "https://syzkaller.appspot.com/bug?id=13849f0d9b1b818b087341691be6cc3ac6a6bfb7" If remove block trace without stop(BLKTRACESTOP) block trace, '__blk_trace_remove' will just set 'q->blk_trace' with NULL. However, debugfs file isn't removed, so will report file already present when call BLKTRACESETUP. static int __blk_trace_remove(struct request_queue *q) { struct blk_trace *bt; bt = rcu_replace_pointer(q->blk_trace, NULL, lockdep_is_held(&q->debugfs_mutex)); if (!bt) return -EINVAL; if (bt->trace_state != Blktrace_running) blk_trace_cleanup(q, bt); return 0; } If do test as follows: step1: ioctl(sda, BLKTRACESETUP, &arg) step2: ioctl(sda, BLKTRACESTART, NULL) step3: ioctl(sda, BLKTRACETEARDOWN, NULL) step4: remove sda There will remove debugfs directory which will remove recursively all file under directory. >> blk_release_queue >> debugfs_remove_recursive(q->debugfs_dir) So all files which created in 'do_blk_trace_setup' are removed, and 'dentry->d_inode' is NULL. But 'q->blk_trace' is still in 'running_trace_lock', 'trace_note_tsk' will traverse 'running_trace_lock' all nodes. >>trace_note_tsk >> trace_note >> relay_reserve >> relay_switch_subbuf >> d_inode(buf->dentry)->i_size To solve above issues, reference commit '5afedf670caf', call 'blk_trace_cleanup' unconditionally in '__blk_trace_remove' and first stop block trace in 'blk_trace_cleanup'. Signed-off-by: Ye Bin Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20221019033602.752383-3-yebin@huaweicloud.com Signed-off-by: Jens Axboe