On 9/9/25 04:07, Johannes Thumshirn wrote: Call BLKTRACESETUP2 ioctl per default and if the kernel does not support this ioctl because it is too old, fall back to calling BLKTRACESETUP.
Signed-off-by: Johannes Thumshirn <[email protected]> --- blktrace.c | 40 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4 deletions(-) diff --git a/blktrace.c b/blktrace.c index 038b2cb..72562fd 100644 --- a/blktrace.c +++ b/blktrace.c @@ -279,7 +279,7 @@ static int max_cpus; static int ncpus; static cpu_set_t *online_cpus; static int pagesize; -static int act_mask = ~0U; +static unsigned long long act_mask = ~0U; ~0ULL ? static int kill_running_trace; static int stop_watch; static int piped_output; @@ -1067,6 +1067,36 @@ static void close_client_connections(void) } } +static int setup_buts2(void) +{ + struct list_head *p; + int ret = 0; + + __list_for_each(p, &devpaths) { + struct blk_user_trace_setup2 buts2; + struct devpath *dpp = list_entry(p, struct devpath, head); + + memset(&buts2, 0, sizeof(buts2)); + buts2.buf_size = buf_size; + buts2.buf_nr = buf_nr; + buts2.act_mask = act_mask; + 1. Original code (BLKTRACESETUP) struct blk_user_trace_setup { char name[32]; /* output */ __u16 act_mask; /* input */ ... }; static int act_mask = ~0U; /* global */ In handle_args(): int act_mask_tmp; if (act_mask_tmp != 0) act_mask = act_mask_tmp; Later in setup_buts(): buts.act_mask = act_mask; Here everything lines up: handle_args() -> int act_mask_tmp act_mask (global) -> int buts.act_mask -> __u16 No truncation issues as long as the mask fits in 16 bits (which it always did in the original design). 2. New code (BLKTRACESETUP2) struct blk_user_trace_setup2 { char name[32]; /* output */ __u64 act_mask; /* input */ ... }; static unsigned long long act_mask = ~0U; /* global changed */ In handle_args() (still unchanged): int act_mask_tmp; if (act_mask_tmp != 0) act_mask = act_mask_tmp; Later in setup_buts2(): buts2.act_mask = act_mask; Here is the issue: handle_args() still uses int act_mask_tmp. global act_mask is now unsigned long long. buts2.act_mask is __u64. above truncation of bits can lead to compiler/tools warnings ? also if in the future|act_mask| uses bits above 31, they could never be set because the input path (|int act_mask_tmp|) can’t represent them ? -ck
