37 lines
1.4 KiB
Diff
37 lines
1.4 KiB
Diff
From cf40d2d8c44a659d09d5c20189aab02f20263e81 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Wed, 29 Mar 2023 09:49:36 +0100
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Subject: [PATCH] fbdev: Don't cancel deferred work if pagelist empty
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Since [1], the fbdev deferred IO framework is careful to cancel
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pending updates on close to prevent dirty pages being accessed after
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they may have been reused. However, this is not necessary in the case
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that the pagelist is empty, and drivers that don't make use of the
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pagelist may have wanted updates cancelled for no good reason.
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Avoid penalising fbdev drivers that don't make use of the pagelist by
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making the cancelling of deferred IO on close conditional on there
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being a non-empty pagelist.
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See: https://github.com/raspberrypi/linux/issues/5398
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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[1] 3efc61d95259 ("fbdev: Fix invalid page access after closing deferred I/O devices")
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---
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drivers/video/fbdev/core/fb_defio.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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--- a/drivers/video/fbdev/core/fb_defio.c
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+++ b/drivers/video/fbdev/core/fb_defio.c
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@@ -317,7 +317,8 @@ static void fb_deferred_io_lastclose(str
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struct page *page;
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int i;
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- flush_delayed_work(&info->deferred_work);
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+ if (!list_empty(&info->fbdefio->pagereflist))
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+ flush_delayed_work(&info->deferred_work);
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/* clear out the mapping that we setup */
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for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
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