Replace kprobe function "blk_account_io_completion" to "blk_account_i…

…o_done" for kernel version >= 5.8.0

The kernel function "blk_account_io_completion" is not available anymore as attach point of Kprobe as of kernel version 5.8.0. Therefore, after discussions, we decided to use function "blk_account_io_done" instead in every kprobe attachment to "blk_account_io_completion".

docs/reference_guide.md

@@ -1784,7 +1784,7 @@ Example:
 b = BPF(text="""
 BPF_HISTOGRAM(dist);
 
-int kprobe__blk_account_io_completion(struct pt_regs *ctx, struct request *req)
+int kprobe__blk_account_io_done(struct pt_regs *ctx, struct request *req)
 {
 	dist.increment(bpf_log2l(req->__data_len / 1024));
 	return 0;
@@ -1835,7 +1835,7 @@ Example:
 b = BPF(text="""
 BPF_HISTOGRAM(dist);
 
-int kprobe__blk_account_io_completion(struct pt_regs *ctx, struct request *req)
+int kprobe__blk_account_io_done(struct pt_regs *ctx, struct request *req)
 {
 	dist.increment(req->__data_len / 1024);
 	return 0;

docs/tutorial_bcc_python_developer.md

@@ -220,7 +220,7 @@ void trace_completion(struct pt_regs *ctx, struct request *req) {
 
 b.attach_kprobe(event="blk_start_request", fn_name="trace_start")
 b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_start")
-b.attach_kprobe(event="blk_account_io_completion", fn_name="trace_completion")
+b.attach_kprobe(event="blk_account_io_done", fn_name="trace_completion")
 [...]
 ```
 
@@ -351,7 +351,7 @@ b = BPF(text="""
 
 BPF_HISTOGRAM(dist);
 
-int kprobe__blk_account_io_completion(struct pt_regs *ctx, struct request *req)
+int kprobe__blk_account_io_done(struct pt_regs *ctx, struct request *req)
 {
 	dist.increment(bpf_log2l(req->__data_len / 1024));
 	return 0;
@@ -374,7 +374,7 @@ b["dist"].print_log2_hist("kbytes")
 A recap from earlier lessons:
 
 - ```kprobe__```: This prefix means the rest will be treated as a kernel function name that will be instrumented using kprobe.
-- ```struct pt_regs *ctx, struct request *req```: Arguments to kprobe. The ```ctx``` is registers and BPF context, the ```req``` is the first argument to the instrumented function: ```blk_account_io_completion()```.
+- ```struct pt_regs *ctx, struct request *req```: Arguments to kprobe. The ```ctx``` is registers and BPF context, the ```req``` is the first argument to the instrumented function: ```blk_account_io_done()```.
 - ```req->__data_len```: Dereferencing that member.
 
 New things to learn:

examples/lua/kprobe-latency.lua

@@ -30,7 +30,7 @@ local lat_map = bpf.map('array', bins)
 local trace_start = bpf.kprobe('myprobe:blk_start_request', function (ptregs)
 	map[ptregs.parm1] = time()
 end, false, -1, 0)
-local trace_end = bpf.kprobe('myprobe2:blk_account_io_completion', function (ptregs)
+local trace_end = bpf.kprobe('myprobe2:blk_account_io_done', function (ptregs)
 	-- The lines below are computing index
 	-- using log10(x)*10 = log2(x)*10/log2(10) = log2(x)*3
 	-- index = 29 ~ 1 usec

examples/tracing/bitehist.py

@@ -25,7 +25,7 @@
 BPF_HISTOGRAM(dist);
 BPF_HISTOGRAM(dist_linear);
 
-int kprobe__blk_account_io_completion(struct pt_regs *ctx, struct request *req)
+int kprobe__blk_account_io_done(struct pt_regs *ctx, struct request *req)
 {
 	dist.increment(bpf_log2l(req->__data_len / 1024));
 	dist_linear.increment(req->__data_len / 1024);

examples/tracing/disksnoop.py

@@ -46,7 +46,7 @@
 if BPF.get_kprobe_functions(b'blk_start_request'):
         b.attach_kprobe(event="blk_start_request", fn_name="trace_start")
 b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_start")
-b.attach_kprobe(event="blk_account_io_completion", fn_name="trace_completion")
+b.attach_kprobe(event="blk_account_io_done", fn_name="trace_completion")
 
 # header
 print("%-18s %-2s %-7s %8s" % ("TIME(s)", "T", "BYTES", "LAT(ms)"))

tools/biosnoop.lua

@@ -126,7 +126,7 @@ return function(BPF, utils)
   bpf:attach_kprobe{event="blk_account_io_start", fn_name="trace_pid_start"}
   bpf:attach_kprobe{event="blk_start_request", fn_name="trace_req_start"}
   bpf:attach_kprobe{event="blk_mq_start_request", fn_name="trace_req_start"}
-  bpf:attach_kprobe{event="blk_account_io_completion",
+  bpf:attach_kprobe{event="blk_account_io_done",
       fn_name="trace_req_completion"}
 
   print("%-14s %-14s %-6s %-7s %-2s %-9s %-7s %7s" % {"TIME(s)", "COMM", "PID",

tools/biosnoop.py

@@ -160,7 +160,7 @@
 if BPF.get_kprobe_functions(b'blk_start_request'):
     b.attach_kprobe(event="blk_start_request", fn_name="trace_req_start")
 b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_req_start")
-b.attach_kprobe(event="blk_account_io_completion",
+b.attach_kprobe(event="blk_account_io_done",
     fn_name="trace_req_completion")
 
 # header

tools/biotop.py

@@ -178,7 +178,7 @@ def signal_ignore(signal_value, frame):
 if BPF.get_kprobe_functions(b'blk_start_request'):
     b.attach_kprobe(event="blk_start_request", fn_name="trace_req_start")
 b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_req_start")
-b.attach_kprobe(event="blk_account_io_completion",
+b.attach_kprobe(event="blk_account_io_done",
     fn_name="trace_req_completion")
 
 print('Tracing... Output every %d secs. Hit Ctrl-C to end' % interval)

tools/old/biosnoop.py

@@ -98,7 +98,7 @@
 b.attach_kprobe(event="blk_account_io_start", fn_name="trace_pid_start")
 b.attach_kprobe(event="blk_start_request", fn_name="trace_req_start")
 b.attach_kprobe(event="blk_mq_start_request", fn_name="trace_req_start")
-b.attach_kprobe(event="blk_account_io_completion",
+b.attach_kprobe(event="blk_account_io_done",
     fn_name="trace_req_completion")
 
 # header