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Re: [PATCH 02/11] treewide: prefer lockfiles on the stack

From
Junio C Hamano <gitster@pobox.com>
Date
Oct 2, 2017, 03:37 UTC
Message-ID
<xmqqlgkuqkyi.fsf@gitster.mtv.corp.google.com>
In-Reply-To
<f241038eeed0f5f8bb346b394495356c20884a39.1506862824.git.martin.agren@gmail.com>
Martin Ågren <martin.agren@gmail.com> writes:
Show 23 quoted lines
> diff --git a/builtin/diff.c b/builtin/diff.c
> index 7e3ebcea3..91995965d 100644
> --- a/builtin/diff.c
> +++ b/builtin/diff.c
> @@ -203,17 +203,16 @@ static int builtin_diff_combined(struct rev_info *revs,
>  
>  static void refresh_index_quietly(void)
>  {
> -	struct lock_file *lock_file;
> +	struct lock_file lock_file = LOCK_INIT;
>  	int fd;
>  
> -	lock_file = xcalloc(1, sizeof(struct lock_file));
> -	fd = hold_locked_index(lock_file, 0);
> +	fd = hold_locked_index(&lock_file, 0);
>  	if (fd < 0)
>  		return;
>  	discard_cache();
>  	read_cache();
>  	refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);
> -	update_index_if_able(&the_index, lock_file);
> +	update_index_if_able(&the_index, &lock_file);
>  }

This is not a show-stopper for this patch series, but just something I noticed, something that used to be unavoidable in the old world order that requires us to leak lockfiles, but now it becomes more obvious.

update_index_if_able() calls write_lock_index() with the COMMIT_LOCK option, but it does so conditionally. When it does not make the call, the lockfile is left behind to be cleaned up by the atexit() handler, but when it does, it is closed and released.

Perhaps update_index_if_able() needs to be further cleaned up to always release the resource held by the lockfile structure? Its caller cannot differentiate (and more importantly, its caller does not want to care) if the _if_able call actually has updated the index or not and act differently afterwards.

Previous: Martin ÅgrenNext: Martin Ågren
Message 6 of 69 in “various lockfile-leaks and -fixes”
  1. 00/11 various lockfile-leaks and -fixesMartin Ågren, Oct 1, 2017
  2. 01/11 sha1_file: do not leak `lock_file`Martin Ågren, Oct 1, 2017
  3. Jeff KingOct 2, 2017
  4. Martin ÅgrenOct 2, 2017
  5. 02/11 treewide: prefer lockfiles on the stackMartin Ågren, Oct 1, 2017
  6. Junio C HamanoOct 2, 2017
  7. Martin ÅgrenOct 2, 2017
  8. Jeff KingOct 2, 2017
  9. 03/11 lockfile: fix documentation on `close_lock_file_gently()`Martin Ågren, Oct 1, 2017
  10. Jeff KingOct 2, 2017
  11. 04/11 tempfile: fix documentation on `delete_tempfile()`Martin Ågren, Oct 1, 2017
  12. Jeff KingOct 2, 2017
  13. 05/11 cache-tree: simplify locking logicMartin Ågren, Oct 1, 2017
  14. Junio C HamanoOct 2, 2017
  15. Jeff KingOct 2, 2017
  16. 06/11 apply: move lockfile into `apply_state`Martin Ågren, Oct 1, 2017
  17. Jeff KingOct 2, 2017
  18. 07/11 apply: remove `newfd` from `struct apply_state`Martin Ågren, Oct 1, 2017
  19. Jeff KingOct 2, 2017
  20. 08/11 cache.h: document `write_locked_index()`Martin Ågren, Oct 1, 2017
  21. 09/11 read-cache: require flags for `write_locked_index()`Martin Ågren, Oct 1, 2017
  22. Junio C HamanoOct 2, 2017
  23. Martin ÅgrenOct 2, 2017
  24. Martin ÅgrenOct 2, 2017
  25. Jeff KingOct 2, 2017
  26. 10/11 read-cache: don't leave dangling pointer in `do_write_index()`Martin Ågren, Oct 1, 2017
  27. Jeff KingOct 2, 2017
  28. Jeff KingOct 2, 2017
  29. 11/11 read-cache: roll back lock on error with `COMMIT_LOCK`Martin Ågren, Oct 1, 2017
  30. Junio C HamanoOct 2, 2017
  31. Junio C HamanoOct 2, 2017
  32. Jeff KingOct 2, 2017
  33. Junio C HamanoOct 2, 2017
  34. Martin ÅgrenOct 2, 2017
  35. Junio C HamanoOct 3, 2017
  36. 00/12 Re: various lockfile-leaks and -fixesMartin Ågren, Oct 5, 2017
  37. 01/12 sha1_file: do not leak `lock_file`Martin Ågren, Oct 5, 2017
  38. Junio C HamanoOct 6, 2017
  39. 02/12 treewide: prefer lockfiles on the stackMartin Ågren, Oct 5, 2017
  40. 03/12 lockfile: fix documentation on `close_lock_file_gently()`Martin Ågren, Oct 5, 2017
  41. 05/12 checkout-index: simplify locking logicMartin Ågren, Oct 5, 2017
  42. Junio C HamanoOct 6, 2017
  43. 06/12 cache-tree: simplify locking logicMartin Ågren, Oct 5, 2017
  44. 07/12 apply: move lockfile into `apply_state`Martin Ågren, Oct 5, 2017
  45. 08/12 apply: remove `newfd` from `struct apply_state`Martin Ågren, Oct 5, 2017
  46. 10/12 read-cache: drop explicit `CLOSE_LOCK`-flagMartin Ågren, Oct 5, 2017
  47. Junio C HamanoOct 6, 2017
  48. Martin ÅgrenOct 6, 2017
  49. 11/12 read-cache: leave lock in right state in `write_locked_index()`Martin Ågren, Oct 5, 2017
  50. Junio C HamanoOct 6, 2017
  51. Martin ÅgrenOct 6, 2017
  52. Junio C HamanoOct 6, 2017
  53. Martin ÅgrenOct 6, 2017
  54. 00/12 Re: various lockfile-leaks and -fixesMartin Ågren, Oct 6, 2017
  55. 01/12 sha1_file: do not leak `lock_file`Martin Ågren, Oct 6, 2017
  56. 02/12 treewide: prefer lockfiles on the stackMartin Ågren, Oct 6, 2017
  57. 04/12 tempfile: fix documentation on `delete_tempfile()`Martin Ågren, Oct 6, 2017
  58. 06/12 cache-tree: simplify locking logicMartin Ågren, Oct 6, 2017
  59. 05/12 checkout-index: simplify locking logicMartin Ågren, Oct 6, 2017
  60. 08/12 apply: remove `newfd` from `struct apply_state`Martin Ågren, Oct 6, 2017
  61. 09/12 cache.h: document `write_locked_index()`Martin Ågren, Oct 6, 2017
  62. 10/12 read-cache: drop explicit `CLOSE_LOCK`-flagMartin Ågren, Oct 6, 2017
  63. 12/12 read_cache: roll back lock in `update_index_if_able()`Martin Ågren, Oct 6, 2017
  64. 11/12 read-cache: leave lock in right state in `write_locked_index()`Martin Ågren, Oct 6, 2017
  65. 03/12 lockfile: fix documentation on `close_lock_file_gently()`Martin Ågren, Oct 6, 2017
  66. 07/12 apply: move lockfile into `apply_state`Martin Ågren, Oct 6, 2017
  67. 09/12 cache.h: document `write_locked_index()`Martin Ågren, Oct 5, 2017
  68. 12/12 read_cache: roll back lock in `update_index_if_able()`Martin Ågren, Oct 5, 2017
  69. 04/12 tempfile: fix documentation on `delete_tempfile()`Martin Ågren, Oct 5, 2017

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