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Wed, 19 Aug 2026 08:19:51 +0000 Message-ID: Date: Wed, 19 Aug 2026 10:19:50 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 06/12] drm/panic: Pass global module parameters to drm_panic_dispatch() To: sashiko-reviews@lists.linux.dev Cc: intel-xe@lists.freedesktop.org, ojeda@kernel.org, linux-hyperv@vger.kernel.org, Frank.Li@kernel.org, intel-gfx@lists.freedesktop.org, wsa+renesas@sang-engineering.com, dri-devel@lists.freedesktop.org, imx@lists.linux.dev References: <20260818125012.468092-1-tzimmermann@suse.de> <20260818125012.468092-7-tzimmermann@suse.de> <20260818130916.110771F000E9@smtp.kernel.org> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNJ1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPsLAjgQTAQgAOAIb AwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftODH AAoJEGgNwR1TC3ojx1wH/0hKGWugiqDgLNXLRD/4TfHBEKmxIrmfu9Z5t7vwUKfwhFL6hqvo lXPJJKQpQ2z8+X2vZm/slsLn7J1yjrOsoJhKABDi+3QWWSGkaGwRJAdPVVyJMfJRNNNIKwVb U6B1BkX2XDKDGffF4TxlOpSQzdtNI/9gleOoUA8+jy8knnDYzjBNOZqLG2FuTdicBXblz0Mf vg41gd9kCwYXDnD91rJU8tzylXv03E75NCaTxTM+FBXPmsAVYQ4GYhhgFt8S2UWMoaaABLDe 7l5FdnLdDEcbmd8uLU2CaG4W2cLrUaI4jz2XbkcPQkqTQ3EB67hYkjiEE6Zy3ggOitiQGcqp j//OwE0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRHUE9eosYb T6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgTRjP+qbU6 3Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+RdhgATnWW GKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zbehDda8lv hFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r12+lqdsA EQEAAcLAdgQYAQgAIAIbDBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftOH6AAoJEGgNwR1T C3ojVSkIALpAPkIJPQoURPb1VWjh34l0HlglmYHvZszJWTXYwavHR8+k6Baa6H7ufXNQtThR yIxJrQLW6rV5lm7TjhffEhxVCn37+cg0zZ3j7zIsSS0rx/aMwi6VhFJA5hfn3T0TtrijKP4A SAQO9xD1Zk9/61JWk8OysuIh7MXkl0fxbRKWE93XeQBhIJHQfnc+YBLprdnxR446Sh8Wn/2D Ya8cavuWf2zrB6cZurs048xe0UbSW5AOSo4V9M0jzYI4nZqTmPxYyXbm30Kvmz0rYVRaitYJ 4kyYYMhuULvrJDMjZRvaNe52tkKAvMevcGdt38H4KSVXAylqyQOW5zvPc4/sq9c= In-Reply-To: <20260818130916.110771F000E9@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_TLS_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:url,suse.de:email,suse.de:mid,suse.de:dkim,imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[renesas]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_SEVEN(0.00)[9]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_NONE(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Queue-Id: 804703EAC X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" Am 18.08.26 um 15:09 schrieb sashiko-bot@kernel.org: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > > Pre-existing issues: > - [High] Concurrent debugfs writes or KUnit tests across multiple DRM devices race on global static buffers without adequate synchronization. A fix would be nice, but is beyond this series. As it affects debugfs and kunit test there's no urgency. > -- > > --- Patch [6]: [PATCH 06/12] drm/panic: Pass global module parameters to drm_panic_dispatch() --- > commit 9f2a1b5158feac614c09a17c83f387591642e034 > Author: Thomas Zimmermann > > drm/panic: Pass global module parameters to drm_panic_dispatch() > > This patch sets the panic type and QR version in draw_panic_plane() as a single > point of truth, passing these values into the individual drawing functions. > In the test case, it always creates a QR code with version 40. > >> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c >> index ede620b27515a..12c39217cbcb5 100644 >> --- a/drivers/gpu/drm/drm_panic.c >> +++ b/drivers/gpu/drm/drm_panic.c > [ ... ] >> @@ -951,6 +955,11 @@ static void draw_panic_plane(struct drm_plane *plane, const char *description) >> #else >> u32 bg_color = 0x00000000; >> #endif >> +#if IS_ENABLED(CONFIG_DRM_PANIC_SCREEN_QR_CODE) >> + unsigned int qr_version = panic_qr_version; >> +#else >> + unsigned int qr_version = 0; >> +#endif >> >> if (!drm_panic_trylock(plane->dev, flags)) >> return; >> @@ -966,7 +975,7 @@ static void draw_panic_plane(struct drm_plane *plane, const char *description) >> >> drm_panic_set_description(description); >> >> - ret = draw_panic_dispatch(&sb, fg_color, bg_color); >> + ret = draw_panic_dispatch(&sb, drm_panic_type, fg_color, bg_color, qr_version); > [Severity: High] > This is a pre-existing issue, but does the per-device locking in > drm_panic_trylock() adequately protect the global buffers? > > Since the lock is per-device (plane->dev->mode_config.panic_lock), concurrent > debugfs writes across multiple DRM devices can still race and mutate global > static variables, such as the zlib stream workspace (struct z_stream_s stream) > or qrbuf1 and qrbuf2. > > If a real kernel panic occurs while a debugfs write is concurrently using these > buffers, the true panic handler could inherit a corrupted zlib workspace state, > which might lead to a recursive fault and failure to display the panic screen. > > Could this be protected by a global lock for non-panic paths? > > [ ... ] >> diff --git a/drivers/gpu/drm/tests/drm_panic_test.c b/drivers/gpu/drm/tests/drm_panic_test.c >> index 969a096ec840f..196496238d231 100644 >> --- a/drivers/gpu/drm/tests/drm_panic_test.c >> +++ b/drivers/gpu/drm/tests/drm_panic_test.c >> @@ -58,7 +58,7 @@ static int draw_panic_screen_kmsg_default(struct drm_scanout_buffer *sb) >> #if IS_ENABLED(CONFIG_DRM_PANIC_SCREEN_QR_CODE) >> static int draw_panic_screen_qr_code_default(struct drm_scanout_buffer *sb) >> { >> - return draw_panic_screen_qr_code(sb, 0x00ffffff, 0x00000000); >> + return draw_panic_screen_qr_code(sb, 0x00ffffff, 0x00000000, 40); >> } >> #endif > [Severity: High] > This isn't a bug introduced by this patch, but do the KUnit tests safely access > the global drawing state? > > It appears the KUnit tests bypass draw_panic_plane() entirely and directly call > drawing functions like draw_panic_screen_qr_code() without acquiring any locks. > Could running the tests race on the global buffers and corrupt the zlib > workspace? > -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)