linux-kernel - [PATCH 5.4 01/85] drm/i915: Break up error capture compression loops with cond

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Message-Id: <20201109125022.683904187@linuxfoundation.org>
Date:   Mon,  9 Nov 2020 13:54:58 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chris Wilson <chris@...is-wilson.co.uk>,
        Mika Kuoppala <mika.kuoppala@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>
Subject: [PATCH 5.4 01/85] drm/i915: Break up error capture compression loops with cond_resched()

From: Chris Wilson <chris@...is-wilson.co.uk>

commit 7d5553147613b50149238ac1385c60e5c7cacb34 upstream.

As the error capture will compress user buffers as directed to by the
user, it can take an arbitrary amount of time and space. Break up the
compression loops with a call to cond_resched(), that will allow other
processes to schedule (avoiding the soft lockups) and also serve as a
warning should we try to make this loop atomic in the future.

Testcase: igt/gem_exec_capture/many-*
Signed-off-by: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@...ux.intel.com>
Cc: stable@...r.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@...ux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200916090059.3189-2-chris@chris-wilson.co.uk
(cherry picked from commit 293f43c80c0027ff9299036c24218ac705ce584e)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/i915/i915_gpu_error.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -307,6 +307,8 @@ static int compress_page(struct compress
 
 		if (zlib_deflate(zstream, Z_NO_FLUSH) != Z_OK)
 			return -EIO;
+
+		cond_resched();
 	} while (zstream->avail_in);
 
 	/* Fallback to uncompressed if we increase size? */
@@ -392,6 +394,7 @@ static int compress_page(struct compress
 	if (!i915_memcpy_from_wc(ptr, src, PAGE_SIZE))
 		memcpy(ptr, src, PAGE_SIZE);
 	dst->pages[dst->page_count++] = ptr;
+	cond_resched();
 
 	return 0;
 }