Attachment 121328 Details for Bug 93891 – 0001-scaled-font-Fix-deadlock-when-recursing-in-_cairo_sc.patch

[patch] 0001-scaled-font-Fix-deadlock-when-recursing-in-_cairo_sc.patch

0001-scaled-font-Fix-deadlock-when-recursing-in-_cairo_sc.patch (text/plain), 2.40 KB, created by Hans Petter Jansson on 2016-01-27 19:06:31 UTC

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Creator: Hans Petter Jansson

Created: 2016-01-27 19:06:31 UTC

Size: 2.40 KB

patch

obsolete

>From 8a6de4f53fb0cf8b8af654c18eadc31ed3a9525e Mon Sep 17 00:00:00 2001
>From: Hans Petter Jansson <hpj@cl.no>
>Date: Wed, 27 Jan 2016 12:55:01 -0600
>Subject: [PATCH] scaled-font: Fix deadlock when recursing in
> _cairo_scaled_font_reset_cache()
>
>The destruction of a scaled font could indirectly trigger the destruction
>of a second scaled font, causing the global cache to be locked twice in
>the same thread.
>
>This is solved by unlinking the font's glyph pages while holding the global
>lock, then releasing the lock before destruction takes place.
>
>Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=93891
>---
> src/cairo-scaled-font.c | 24 ++++++++++++++++++------
> 1 file changed, 18 insertions(+), 6 deletions(-)
>
>diff --git a/src/cairo-scaled-font.c b/src/cairo-scaled-font.c
>index ac80c97..a22b36e 100644
>--- a/src/cairo-scaled-font.c
>+++ b/src/cairo-scaled-font.c
>@@ -818,23 +818,35 @@ _cairo_scaled_font_thaw_cache (cairo_scaled_font_t *scaled_font)
> void
> _cairo_scaled_font_reset_cache (cairo_scaled_font_t *scaled_font)
> {
>+    cairo_scaled_glyph_page_t *page;
>+
>     CAIRO_MUTEX_LOCK (scaled_font->mutex);
>     assert (! scaled_font->cache_frozen);
>     assert (! scaled_font->global_cache_frozen);
>     CAIRO_MUTEX_LOCK (_cairo_scaled_glyph_page_cache_mutex);
>-    while (! cairo_list_is_empty (&scaled_font->glyph_pages)) {
>-	cairo_scaled_glyph_page_t *page =
>-	    cairo_list_first_entry (&scaled_font->glyph_pages,
>-				    cairo_scaled_glyph_page_t,
>-				    link);
> 
>+    cairo_list_foreach_entry (page,
>+			      cairo_scaled_glyph_page_t,
>+			      &scaled_font->glyph_pages,
>+			      link) {
> 	cairo_scaled_glyph_page_cache.size -= page->cache_entry.size;
> 	_cairo_hash_table_remove (cairo_scaled_glyph_page_cache.hash_table,
> 				  (cairo_hash_entry_t *) &page->cache_entry);
>+    }
> 
>+    CAIRO_MUTEX_UNLOCK (_cairo_scaled_glyph_page_cache_mutex);
>+
>+    /* Destroy scaled_font's pages while holding its lock only, and not the
>+     * global page cache lock. The destructor can cause us to recurse and
>+     * end up back here for a different scaled_font. */
>+
>+    while (! cairo_list_is_empty (&scaled_font->glyph_pages)) {
>+	page = cairo_list_first_entry (&scaled_font->glyph_pages,
>+				       cairo_scaled_glyph_page_t,
>+				       link);
> 	_cairo_scaled_glyph_page_destroy (scaled_font, page);
>     }
>-    CAIRO_MUTEX_UNLOCK (_cairo_scaled_glyph_page_cache_mutex);
>+
>     CAIRO_MUTEX_UNLOCK (scaled_font->mutex);
> }
> 
>-- 
>1.8.4.5
>

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Attachments on bug 93891: 121328 | 125494 | 125495

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