Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 316 insertions, 0 deletions

diff --git a/Documentation/sphinx/automarkup.py b/Documentation/sphinx/automarkup.py
new file mode 100644
index 000000000..c2227ab0a
--- /dev/null
+++ b/Documentation/sphinx/automarkup.py
@@ -0,0 +1,316 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2019 Jonathan Corbet <corbet@lwn.net>
+#
+# Apply kernel-specific tweaks after the initial document processing
+# has been done.
+#
+from docutils import nodes
+import sphinx
+from sphinx import addnodes
+from sphinx.errors import NoUri
+import re
+from itertools import chain
+
+from kernel_abi import get_kernel_abi
+
+#
+# Regex nastiness.  Of course.
+# Try to identify "function()" that's not already marked up some
+# other way.  Sphinx doesn't like a lot of stuff right after a
+# :c:func: block (i.e. ":c:func:`mmap()`s" flakes out), so the last
+# bit tries to restrict matches to things that won't create trouble.
+#
+RE_function = re.compile(r'\b(([a-zA-Z_]\w+)\(\))', flags=re.ASCII)
+
+#
+# Sphinx 3 uses a different C role for each one of struct, union, enum and
+# typedef
+#
+RE_struct = re.compile(r'\b(struct)\s+([a-zA-Z_]\w+)', flags=re.ASCII)
+RE_union = re.compile(r'\b(union)\s+([a-zA-Z_]\w+)', flags=re.ASCII)
+RE_enum = re.compile(r'\b(enum)\s+([a-zA-Z_]\w+)', flags=re.ASCII)
+RE_typedef = re.compile(r'\b(typedef)\s+([a-zA-Z_]\w+)', flags=re.ASCII)
+
+#
+# Detects a reference to a documentation page of the form Documentation/... with
+# an optional extension
+#
+RE_doc = re.compile(r'(\bDocumentation/)?((\.\./)*[\w\-/]+)\.(rst|txt)')
+RE_abi_file = re.compile(r'(\bDocumentation/ABI/[\w\-/]+)')
+RE_abi_symbol = re.compile(r'(\b/(sys|config|proc)/[\w\-/]+)')
+
+RE_namespace = re.compile(r'^\s*..\s*c:namespace::\s*(\S+)\s*$')
+
+#
+# Reserved C words that we should skip when cross-referencing
+#
+Skipnames = [ 'for', 'if', 'register', 'sizeof', 'struct', 'unsigned' ]
+
+#
+# Common English words that should not be recognized as C identifiers
+# when following struct/union/enum/typedef keywords.
+# Example: "a simple struct that" in workqueue.rst should not be marked as code.
+#
+Skipidentifiers = [ 'that', 'which', 'where', 'whose' ]
+
+#
+# Many places in the docs refer to common system calls.  It is
+# pointless to try to cross-reference them and, as has been known
+# to happen, somebody defining a function by these names can lead
+# to the creation of incorrect and confusing cross references.  So
+# just don't even try with these names.
+#
+Skipfuncs = [ 'open', 'close', 'read', 'write', 'fcntl', 'mmap',
+              'select', 'poll', 'fork', 'execve', 'clone', 'ioctl',
+              'socket' ]
+
+c_namespace = ''
+
+#
+# Detect references to commits.
+#
+RE_git = re.compile(r'commit\s+(?P<rev>[0-9a-f]{12,40})(?:\s+\(".*?"\))?',
+    flags=re.IGNORECASE | re.DOTALL)
+
+def markup_refs(docname, app, node):
+    t = node.astext()
+    done = 0
+    repl = [ ]
+    #
+    # Associate each regex with the function that will markup its matches
+    #
+
+    markup_func = {RE_doc: markup_doc_ref,
+                           RE_abi_file: markup_abi_file_ref,
+                           RE_abi_symbol: markup_abi_ref,
+                           RE_function: markup_func_ref_sphinx3,
+                           RE_struct: markup_c_ref,
+                           RE_union: markup_c_ref,
+                           RE_enum: markup_c_ref,
+                           RE_typedef: markup_c_ref,
+                           RE_git: markup_git}
+
+    match_iterators = [regex.finditer(t) for regex in markup_func]
+    #
+    # Sort all references by the starting position in text
+    #
+    sorted_matches = sorted(chain(*match_iterators), key=lambda m: m.start())
+    for m in sorted_matches:
+        #
+        # Include any text prior to match as a normal text node.
+        #
+        if m.start() > done:
+            repl.append(nodes.Text(t[done:m.start()]))
+
+        #
+        # Call the function associated with the regex that matched this text and
+        # append its return to the text
+        #
+        repl.append(markup_func[m.re](docname, app, m))
+
+        done = m.end()
+    if done < len(t):
+        repl.append(nodes.Text(t[done:]))
+    return repl
+
+#
+# Keep track of cross-reference lookups that failed so we don't have to
+# do them again.
+#
+failed_lookups = { }
+def failure_seen(target):
+    return (target) in failed_lookups
+def note_failure(target):
+    failed_lookups[target] = True
+
+#
+# In sphinx3 we can cross-reference to C macro and function, each one with its
+# own C role, but both match the same regex, so we try both.
+#
+def markup_func_ref_sphinx3(docname, app, match):
+    base_target = match.group(2)
+    target_text = nodes.Text(match.group(0))
+    possible_targets = [base_target]
+    # Check if this document has a namespace, and if so, try
+    # cross-referencing inside it first.
+    if c_namespace:
+        possible_targets.insert(0, c_namespace + "." + base_target)
+
+    if base_target not in Skipnames:
+        for target in possible_targets:
+            if (target not in Skipfuncs) and not failure_seen(target):
+                lit_text = nodes.literal(classes=['xref', 'c', 'c-func'])
+                lit_text += target_text
+                xref = add_and_resolve_xref(app, docname, 'c', 'function',
+                                            target, contnode=lit_text)
+                if xref:
+                    return xref
+                note_failure(target)
+
+    return target_text
+
+def markup_c_ref(docname, app, match):
+    class_str = {RE_struct: 'c-struct',
+                 RE_union: 'c-union',
+                 RE_enum: 'c-enum',
+                 RE_typedef: 'c-type',
+                 }
+    reftype_str = {RE_struct: 'struct',
+                   RE_union: 'union',
+                   RE_enum: 'enum',
+                   RE_typedef: 'type',
+                   }
+
+    base_target = match.group(2)
+    target_text = nodes.Text(match.group(0))
+    possible_targets = [base_target]
+    # Check if this document has a namespace, and if so, try
+    # cross-referencing inside it first.
+    if c_namespace:
+        possible_targets.insert(0, c_namespace + "." + base_target)
+
+    # Skip common English words that match identifier pattern but are not C code.
+    if base_target in Skipidentifiers:
+        return target_text
+
+    if base_target not in Skipnames:
+        for target in possible_targets:
+            if not (match.re == RE_function and target in Skipfuncs):
+                lit_text = nodes.literal(classes=['xref', 'c', class_str[match.re]])
+                lit_text += target_text
+                xref = add_and_resolve_xref(app, docname, 'c',
+                                            reftype_str[match.re], target,
+                                            contnode=lit_text)
+                if xref:
+                    return xref
+
+    return target_text
+
+#
+# Try to replace a documentation reference of the form Documentation/... with a
+# cross reference to that page
+#
+def markup_doc_ref(docname, app, match):
+    absolute = match.group(1)
+    target = match.group(2)
+    if absolute:
+       target = "/" + target
+
+    xref = add_and_resolve_xref(app, docname, 'std', 'doc', target)
+    if xref:
+        return xref
+    else:
+        return nodes.Text(match.group(0))
+
+#
+# Try to replace a documentation reference for ABI symbols and files
+# with a cross reference to that page
+#
+def markup_abi_ref(docname, app, match, warning=False):
+    kernel_abi = get_kernel_abi()
+
+    fname = match.group(1)
+    target = kernel_abi.xref(fname)
+
+    # Kernel ABI doesn't describe such file or symbol
+    if not target:
+        if warning:
+            kernel_abi.log.warning("%s not found", fname)
+        return nodes.Text(match.group(0))
+
+    xref = add_and_resolve_xref(app, docname, 'std', 'ref', target)
+    if xref:
+        return xref
+    else:
+        return nodes.Text(match.group(0))
+
+def add_and_resolve_xref(app, docname, domain, reftype, target, contnode=None):
+    #
+    # Go through the dance of getting an xref out of the corresponding domain
+    #
+    dom_obj = app.env.domains[domain]
+    pxref = addnodes.pending_xref('', refdomain = domain, reftype = reftype,
+                                  reftarget = target, modname = None,
+                                  classname = None, refexplicit = False)
+
+    #
+    # XXX The Latex builder will throw NoUri exceptions here,
+    # work around that by ignoring them.
+    #
+    try:
+        xref = dom_obj.resolve_xref(app.env, docname, app.builder, reftype,
+                                    target, pxref, contnode)
+    except NoUri:
+        xref = None
+
+    if xref:
+        return xref
+    #
+    # We didn't find the xref; if a container node was supplied,
+    # mark it as a broken xref
+    #
+    if contnode:
+        contnode['classes'].append("broken_xref")
+    return contnode
+
+#
+# Variant of markup_abi_ref() that warns when a reference is not found
+#
+def markup_abi_file_ref(docname, app, match):
+    return markup_abi_ref(docname, app, match, warning=True)
+
+
+def get_c_namespace(app, docname):
+    source = app.env.doc2path(docname)
+    with open(source) as f:
+        for l in f:
+            match = RE_namespace.search(l)
+            if match:
+                return match.group(1)
+    return ''
+
+def markup_git(docname, app, match):
+    # While we could probably assume that we are running in a git
+    # repository, we can't know for sure, so let's just mechanically
+    # turn them into git.kernel.org links without checking their
+    # validity. (Maybe we can do something in the future to warn about
+    # these references if this is explicitly requested.)
+    text = match.group(0)
+    rev = match.group('rev')
+    return nodes.reference('', nodes.Text(text),
+        refuri=f'https://git.kernel.org/torvalds/c/{rev}')
+
+def auto_markup(app, doctree, name):
+    global c_namespace
+    c_namespace = get_c_namespace(app, name)
+    def text_but_not_a_reference(node):
+        # The nodes.literal test catches ``literal text``, its purpose is to
+        # avoid adding cross-references to functions that have been explicitly
+        # marked with cc:func:.
+        if not isinstance(node, nodes.Text) or isinstance(node.parent, nodes.literal):
+            return False
+
+        child_of_reference = False
+        parent = node.parent
+        while parent:
+            if isinstance(parent, nodes.Referential):
+                child_of_reference = True
+                break
+            parent = parent.parent
+        return not child_of_reference
+
+    #
+    # This loop could eventually be improved on.  Someday maybe we
+    # want a proper tree traversal with a lot of awareness of which
+    # kinds of nodes to prune.  But this works well for now.
+    #
+    for para in doctree.traverse(nodes.paragraph):
+        for node in para.traverse(condition=text_but_not_a_reference):
+            node.parent.replace(node, markup_refs(name, app, node))
+
+def setup(app):
+    app.connect('doctree-resolved', auto_markup)
+    return {
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+        }