[Bug tapsets/28184] New: task_fd_lookup failed on linux 5.11

[Bug tapsets/28184] New: task_fd_lookup failed on linux 5.11

[lijunlong at openresty dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28184

            Bug ID: 28184
           Summary: task_fd_lookup failed on linux 5.11
           Product: systemtap
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tapsets
          Assignee: systemtap at sourceware dot org
          Reporter: lijunlong at openresty dot com
  Target Milestone: ---

Created attachment 13589
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13589&action=edit
fcheck_files

linux 5.11, fcheck_files was removed and replace by the following functions.

the patch in the attachment solve this problem.

``` c
/*
 * The caller must ensure that fd table isn't shared or hold rcu or file lock
 */
static inline struct file *files_lookup_fd_raw(struct files_struct *files,
unsigned int fd)
{
        struct fdtable *fdt = rcu_dereference_raw(files->fdt);

        if (fd < fdt->max_fds) {
                fd = array_index_nospec(fd, fdt->max_fds);
                return rcu_dereference_raw(fdt->fd[fd]);
        }
        return NULL;
}

static inline struct file *files_lookup_fd_locked(struct files_struct *files,
unsigned int fd)
{
        RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock),
                           "suspicious rcu_dereference_check() usage");
        return files_lookup_fd_raw(files, fd);
}

static inline struct file *files_lookup_fd_rcu(struct files_struct *files,
unsigned int fd)
{
        RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
                           "suspicious rcu_dereference_check() usage");
        return files_lookup_fd_raw(files, fd);
}
```

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[Bug tapsets/28184] task_fd_lookup failed on linux 5.11

[lijunlong at openresty dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28184

--- Comment #1 from lijunlong <lijunlong at openresty dot com> ---
Created attachment 13592
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13592&action=edit
detect files_lookup_fd_raw api

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[Bug tapsets/28184] task_fd_lookup failed on linux 5.11

[lijunlong at openresty dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28184

lijunlong <lijunlong at openresty dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #13589|0                           |1
        is obsolete|                            |
  Attachment #13592|0                           |1
        is obsolete|                            |
                 CC|                            |lijunlong at openresty dot com

--- Comment #2 from lijunlong <lijunlong at openresty dot com> ---
Created attachment 13593
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13593&action=edit
detect api files_lookup_fd_raw

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[Bug tapsets/28184] task_fd_lookup failed on linux 5.11

[lijunlong at openresty dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28184

lijunlong <lijunlong at openresty dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #13593|0                           |1
        is obsolete|                            |

--- Comment #3 from lijunlong <lijunlong at openresty dot com> ---
Created attachment 13595
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13595&action=edit
detect api files_lookup_fd_raw

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[Bug tapsets/28184] task_fd_lookup failed on linux 5.11

[scox at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28184

Stan Cox <scox at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |scox at redhat dot com
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Stan Cox <scox at redhat dot com> ---
commit: f2c147767

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