Re: [PATCH 5/7] printk: Make %pS and friends print module build ID

Quoting Steven Rostedt (2021-03-01 18:43:19)

On Mon,  1 Mar 2021 09:47:47 -0800
Stephen Boyd [off-list ref] wrote:

quoted

The %pS printk format (among some others) is used to print kernel
addresses symbolically. When the kernel prints an address inside of a
module, the kernel prints the addresses' symbol name along with the
module's name that contains the address. Let's make kernel stacktraces
easier to identify on KALLSYMS builds by including the build ID of a
module when we print the address.

Please no!

This kills the output of tracing with offset, and can possibly break
scripts. I don't want to look at traces like this!

          <idle>-0       [004] ..s1   353.842577: ipv4_conntrack_in+0x0/0x10 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_hook_slow+0x40/0xb0
          <idle>-0       [004] ..s1   353.842577: nf_conntrack_in+0x0/0x5c0 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_hook_slow+0x40/0xb0
          <idle>-0       [004] ..s1   353.842577: get_l4proto+0x0/0x190 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_conntrack_in+0x92/0x5c0 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051)
          <idle>-0       [004] ..s1   353.842577: nf_ct_get_tuple+0x0/0x240 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_conntrack_in+0xec/0x5c0 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051)
          <idle>-0       [004] ..s1   353.842577: hash_conntrack_raw+0x0/0x170 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_conntrack_in+0x28c/0x5c0 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051)
          <idle>-0       [004] ..s1   353.842578: __nf_conntrack_find_get.isra.0+0x0/0x2f0 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_conntrack_in+0x29d/0x5c0 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051)
          <idle>-0       [004] ..s1   353.842578: nf_conntrack_tcp_packet+0x0/0x1760 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_conntrack_in+0x3c8/0x5c0 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051)
          <idle>-0       [004] ..s2   353.842578: nf_ct_seq_offset+0x0/0x40 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_conntrack_tcp_packet+0x26d/0x1760 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051)
          <idle>-0       [004] ..s1   353.842578: __nf_ct_refresh_acct+0x0/0x50 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051) <-nf_conntrack_tcp_packet+0x558/0x1760 [nf_conntrack] (3b39eb771b2566331887f671c741f90bfba0b051)

 NACK!

Heh, OK. Would adding a new printk format work then? From after the cut:

Yet another alternative is to add a printk format like %pSB for
backtrace prints. This would require a handful of architecture updates
and I'm not sure it's worth the effort for that.

Or maybe take the approach of putting all the linked in module build IDs
in the "Modules linked in:" section? But as I said in the commit text
that can become quite verbose. Looking forward to your suggestions here.