linux/samples
Linus Torvalds ad584d73a2 Tracing updates for 6.9:
Main user visible change:
 
 - User events can now have "multi formats"
 
   The current user events have a single format. If another event is created
   with a different format, it will fail to be created. That is, once an
   event name is used, it cannot be used again with a different format. This
   can cause issues if a library is using an event and updates its format.
   An application using the older format will prevent an application using
   the new library from registering its event.
 
   A task could also DOS another application if it knows the event names, and
   it creates events with different formats.
 
   The multi-format event is in a different name space from the single
   format. Both the event name and its format are the unique identifier.
   This will allow two different applications to use the same user event name
   but with different payloads.
 
 - Added support to have ftrace_dump_on_oops dump out instances and
   not just the main top level tracing buffer.
 
 Other changes:
 
 - Add eventfs_root_inode
 
   Only the root inode has a dentry that is static (never goes away) and
   stores it upon creation. There's no reason that the thousands of other
   eventfs inodes should have a pointer that never gets set in its
   descriptor. Create a eventfs_root_inode desciptor that has a eventfs_inode
   descriptor and a dentry pointer, and only the root inode will use this.
 
 - Added WARN_ON()s in eventfs
 
   There's some conditionals remaining in eventfs that should never be hit,
   but instead of removing them, add WARN_ON() around them to make sure that
   they are never hit.
 
 - Have saved_cmdlines allocation also include the map_cmdline_to_pid array
 
   The saved_cmdlines structure allocates a large amount of data to hold its
   mappings. Within it, it has three arrays. Two are already apart of it:
   map_pid_to_cmdline[] and saved_cmdlines[]. More memory can be saved by
   also including the map_cmdline_to_pid[] array as well.
 
 - Restructure __string() and __assign_str() macros used in TRACE_EVENT().
 
   Dynamic strings in TRACE_EVENT() are declared with:
 
       __string(name, source)
 
   And assigned with:
 
      __assign_str(name, source)
 
   In the tracepoint callback of the event, the __string() is used to get the
   size needed to allocate on the ring buffer and __assign_str() is used to
   copy the string into the ring buffer. There's a helper structure that is
   created in the TRACE_EVENT() macro logic that will hold the string length
   and its position in the ring buffer which is created by __string().
 
   There are several trace events that have a function to create the string
   to save. This function is executed twice. Once for __string() and again
   for __assign_str(). There's no reason for this. The helper structure could
   also save the string it used in __string() and simply copy that into
   __assign_str() (it also already has its length).
 
   By using the structure to store the source string for the assignment, it
   means that the second argument to __assign_str() is no longer needed.
 
   It will be removed in the next merge window, but for now add a warning if
   the source string given to __string() is different than the source string
   given to __assign_str(), as the source to __assign_str() isn't even used
   and will be going away.
 
 - Added checks to make sure that the source of __string() is also the
   source of __assign_str() so that it can be safely removed in the next
   merge window.
 
   Included fixes that the above check found.
 
 - Other minor clean ups and fixes
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Merge tag 'trace-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:
 "Main user visible change:

   - User events can now have "multi formats"

     The current user events have a single format. If another event is
     created with a different format, it will fail to be created. That
     is, once an event name is used, it cannot be used again with a
     different format. This can cause issues if a library is using an
     event and updates its format. An application using the older format
     will prevent an application using the new library from registering
     its event.

     A task could also DOS another application if it knows the event
     names, and it creates events with different formats.

     The multi-format event is in a different name space from the single
     format. Both the event name and its format are the unique
     identifier. This will allow two different applications to use the
     same user event name but with different payloads.

   - Added support to have ftrace_dump_on_oops dump out instances and
     not just the main top level tracing buffer.

  Other changes:

   - Add eventfs_root_inode

     Only the root inode has a dentry that is static (never goes away)
     and stores it upon creation. There's no reason that the thousands
     of other eventfs inodes should have a pointer that never gets set
     in its descriptor. Create a eventfs_root_inode desciptor that has a
     eventfs_inode descriptor and a dentry pointer, and only the root
     inode will use this.

   - Added WARN_ON()s in eventfs

     There's some conditionals remaining in eventfs that should never be
     hit, but instead of removing them, add WARN_ON() around them to
     make sure that they are never hit.

   - Have saved_cmdlines allocation also include the map_cmdline_to_pid
     array

     The saved_cmdlines structure allocates a large amount of data to
     hold its mappings. Within it, it has three arrays. Two are already
     apart of it: map_pid_to_cmdline[] and saved_cmdlines[]. More memory
     can be saved by also including the map_cmdline_to_pid[] array as
     well.

   - Restructure __string() and __assign_str() macros used in
     TRACE_EVENT()

     Dynamic strings in TRACE_EVENT() are declared with:

         __string(name, source)

     And assigned with:

        __assign_str(name, source)

     In the tracepoint callback of the event, the __string() is used to
     get the size needed to allocate on the ring buffer and
     __assign_str() is used to copy the string into the ring buffer.
     There's a helper structure that is created in the TRACE_EVENT()
     macro logic that will hold the string length and its position in
     the ring buffer which is created by __string().

     There are several trace events that have a function to create the
     string to save. This function is executed twice. Once for
     __string() and again for __assign_str(). There's no reason for
     this. The helper structure could also save the string it used in
     __string() and simply copy that into __assign_str() (it also
     already has its length).

     By using the structure to store the source string for the
     assignment, it means that the second argument to __assign_str() is
     no longer needed.

     It will be removed in the next merge window, but for now add a
     warning if the source string given to __string() is different than
     the source string given to __assign_str(), as the source to
     __assign_str() isn't even used and will be going away.

   - Added checks to make sure that the source of __string() is also the
     source of __assign_str() so that it can be safely removed in the
     next merge window.

     Included fixes that the above check found.

   - Other minor clean ups and fixes"

* tag 'trace-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (34 commits)
  tracing: Add __string_src() helper to help compilers not to get confused
  tracing: Use strcmp() in __assign_str() WARN_ON() check
  tracepoints: Use WARN() and not WARN_ON() for warnings
  tracing: Use div64_u64() instead of do_div()
  tracing: Support to dump instance traces by ftrace_dump_on_oops
  tracing: Remove second parameter to __assign_rel_str()
  tracing: Add warning if string in __assign_str() does not match __string()
  tracing: Add __string_len() example
  tracing: Remove __assign_str_len()
  ftrace: Fix most kernel-doc warnings
  tracing: Decrement the snapshot if the snapshot trigger fails to register
  tracing: Fix snapshot counter going between two tracers that use it
  tracing: Use EVENT_NULL_STR macro instead of open coding "(null)"
  tracing: Use ? : shortcut in trace macros
  tracing: Do not calculate strlen() twice for __string() fields
  tracing: Rework __assign_str() and __string() to not duplicate getting the string
  cxl/trace: Properly initialize cxl_poison region name
  net: hns3: tracing: fix hclgevf trace event strings
  drm/i915: Add missing ; to __assign_str() macros in tracepoint code
  NFSD: Fix nfsd_clid_class use of __string_len() macro
  ...
2024-03-18 15:11:44 -07:00
..
acrn
auxdisplay
binderfs
bpf bpf-next-for-netdev 2024-03-02 20:50:59 -08:00
cgroup samples/cgroup: add .gitignore file for generated samples 2024-01-24 11:52:40 -08:00
configfs
connector
coresight
fanotify
fprobe fprobe: Pass return address to the handlers 2023-06-06 21:39:55 +09:00
ftrace RISC-V Patches for the 6.8 Merge Window, Part 4 2024-01-20 11:06:04 -08:00
hid bpf: Replace deprecated -target with --target= for Clang 2023-06-29 15:46:17 +02:00
hidraw
hw_breakpoint samples/hw_breakpoint: mark sample_hbp as static 2023-07-26 11:17:19 -07:00
kdb
kfifo
kmemleak kmemleak-test: drop __init to get better backtrace 2023-06-09 16:25:40 -07:00
kobject
kprobes samples: kprobes: Fixes a typo 2023-10-10 01:00:50 +09:00
landlock samples/landlock: Don't error out if a file path cannot be opened 2024-03-08 18:22:18 +01:00
livepatch
mei
nitro_enclaves
pfsm samples: Add userspace example for TI TPS6594 PFSM 2023-06-15 13:41:53 +02:00
pidfd
pktgen samples: pktgen: fix append mode failed issue 2023-07-03 09:15:26 +01:00
qmi
rpmsg
rust
seccomp samples: user-trap: fix strict-aliasing warning 2024-02-12 10:42:02 -08:00
timers
trace_events tracing: Remove second parameter to __assign_rel_str() 2024-03-18 10:33:05 -04:00
trace_printk
uhid
user_events
v4l media updates for v6.8-rc1 2024-01-12 14:29:48 -08:00
vfio-mdev vfio/mbochs: make mbochs_class constant 2024-03-05 15:15:27 -07:00
vfs
watch_queue
watchdog
Kconfig samples: introduce new samples subdir for cgroup 2023-12-10 16:51:54 -08:00
Makefile samples: introduce new samples subdir for cgroup 2023-12-10 16:51:54 -08:00