When using IO_CMD_{PREAD,PWRITE} aio_nbytes is the size of a single buffer aio_buf. Previously the script logged unrelated memory contents from userspace: [ 0 sanlock(8214):] io_submit(140589225578496, 1, 0x7fdd5fefc718) iocb[ 0]=0x7fdd58000b70, fd=16, opcode=0, offset=0, nbytes=1048576, buf=0x7fdd5c5f6000 iovec[ 0]=0x7fdd5c5f6000, base=0x3000412212010, len=16 iovec[ 1]=0x7fdd5c5f6010, base=0x0, len=1 iovec[ 2]=0x7fdd5c5f6020, base=0x1, len=16 ... Now we trace iovecs only when using IO_CMD_{PREADV,PWITEV}: [ 0 sanlock(8397):] io_submit(140589225566208, 1, 0x7fdd5e6f9718) iocb[ 0]=0x7fdd48000b70, fd=19, opcode=0, offset=0, nbytes=1048576, buf=0x7fdd5c3f2000 [ 0 sanlock(8397):] io_submit(140589225566208, 1, 0x7fdd5e6f9718) iocb[ 0]=0x7fdd48000b70, fd=19, opcode=1, offset=512, nbytes=512, buf=0x7fdd4810a000 Signed-off-by: Nir Soffer <nsoffer@redhat.com> --- testsuite/systemtap.examples/io/traceaio.stp | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/testsuite/systemtap.examples/io/traceaio.stp b/testsuite/systemtap.examples/io/traceaio.stp index 126ea9c3c..dd123858e 100755 --- a/testsuite/systemtap.examples/io/traceaio.stp +++ b/testsuite/systemtap.examples/io/traceaio.stp @@ -8,6 +8,10 @@ # published by the Free Software Foundation. # +# From <linux/aio_abi.h> +global IOCB_CMD_PREADV = 7 +global IOCB_CMD_PWRITEV = 8 + probe begin { println("Tracing started"); } @@ -27,12 +31,14 @@ probe syscall.io_submit printf(" iocb[%4d]=%p, fd=%d, opcode=%d, offset=%d, nbytes=%d, buf=%p\n", i, iocbp, fd, opcode, offset, nbytes, buf) - for (j = 0; j < nbytes; j++) { - iovecp = &@cast(buf, "iovec", "kernel")[j] - base = user_uint64(&@cast(iovecp, "iovec", "kernel")->iov_base) - len = user_uint32(&@cast(iovecp, "iovec", "kernel")->iov_len) - printf(" iovec[%4d]=%p, base=%p, len=%d\n", - j, iovecp, base, len) + if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV) { + for (j = 0; j < nbytes; j++) { + iovecp = &@cast(buf, "iovec", "kernel")[j] + base = user_uint64(&@cast(iovecp, "iovec", "kernel")->iov_base) + len = user_uint32(&@cast(iovecp, "iovec", "kernel")->iov_len) + printf(" iovec[%4d]=%p, base=%p, len=%d\n", + j, iovecp, base, len) + } } } } -- 2.31.1