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[PATCH] rpmsg: core: fix race in driver_override_show() and use core helper

by Gui-Dong Han

The driver_override_show function reads the driver_override string without holding the device_lock. However, the store function modifies and frees the string while holding the device_lock. This creates a race condition where the string can be freed by the store function while being read by the show function, leading to a use-after-free. To fix this, replace the rpmsg_string_attr macro with explicit show and store functions. The new driver_override_store uses the standard driver_set_override helper. Since the introduction of driver_set_override, the comments in include/linux/rpmsg.h have stated that this helper must be used to set or clear driver_override, but the implementation was not updated until now. Because driver_set_override modifies and frees the string while holding the device_lock, the new driver_override_show now correctly holds the device_lock during the read operation to prevent the race. Additionally, since rpmsg_string_attr has only ever been used for driver_override, removing the macro simplifies the code. Fixes: 39e47767ec9b ("rpmsg: Add driver_override device attribute for rpmsg_device") Cc: stable(a)vger.kernel.org Signed-off-by: Gui-Dong Han <hanguidong02(a)gmail.com> --- I verified this with a stress test that continuously writes/reads the attribute. It triggered KASAN and leaked bytes like a0 f4 81 9f a3 ff ff (likely kernel pointers). Since driver_override is world-readable (0644), this allows unprivileged users to leak kernel pointers and bypass KASLR. Similar races were fixed in other buses (e.g., commits 9561475db680 and 91d44c1afc61). Currently, 9 of 11 buses handle this correctly; this patch fixes one of the remaining two. --- drivers/rpmsg/rpmsg_core.c | 66 ++++++++++++++++---------------------- 1 file changed, 27 insertions(+), 39 deletions(-) diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c index 5d661681a9b6..96964745065b 100644 --- a/drivers/rpmsg/rpmsg_core.c +++ b/drivers/rpmsg/rpmsg_core.c @@ -352,50 +352,38 @@ field##_show(struct device *dev, \ } \ static DEVICE_ATTR_RO(field); -#define rpmsg_string_attr(field, member) \ -static ssize_t \ -field##_store(struct device *dev, struct device_attribute *attr, \ - const char *buf, size_t sz) \ -{ \ - struct rpmsg_device *rpdev = to_rpmsg_device(dev); \ - const char *old; \ - char *new; \ - \ - new = kstrndup(buf, sz, GFP_KERNEL); \ - if (!new) \ - return -ENOMEM; \ - new[strcspn(new, "\n")] = '\0'; \ - \ - device_lock(dev); \ - old = rpdev->member; \ - if (strlen(new)) { \ - rpdev->member = new; \ - } else { \ - kfree(new); \ - rpdev->member = NULL; \ - } \ - device_unlock(dev); \ - \ - kfree(old); \ - \ - return sz; \ -} \ -static ssize_t \ -field##_show(struct device *dev, \ - struct device_attribute *attr, char *buf) \ -{ \ - struct rpmsg_device *rpdev = to_rpmsg_device(dev); \ - \ - return sprintf(buf, "%s\n", rpdev->member); \ -} \ -static DEVICE_ATTR_RW(field) - /* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */ rpmsg_show_attr(name, id.name, "%s\n"); rpmsg_show_attr(src, src, "0x%x\n"); rpmsg_show_attr(dst, dst, "0x%x\n"); rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n"); -rpmsg_string_attr(driver_override, driver_override); + +static ssize_t driver_override_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct rpmsg_device *rpdev = to_rpmsg_device(dev); + int ret; + + ret = driver_set_override(dev, &rpdev->driver_override, buf, count); + if (ret) + return ret; + + return count; +} + +static ssize_t driver_override_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct rpmsg_device *rpdev = to_rpmsg_device(dev); + ssize_t len; + + device_lock(dev); + len = sysfs_emit(buf, "%s\n", rpdev->driver_override); + device_unlock(dev); + return len; +} +static DEVICE_ATTR_RW(driver_override); static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, char *buf) -- 2.43.0

1 week, 4 days

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Re: Patch "RAS: Report all ARM processor CPER information to userspace" has been added to the 6.18-stable tree

by Mauro Carvalho Chehab

Hi Sacha, Em Sat, 13 Dec 2025 04:49:42 -0500 Sasha Levin <sashal(a)kernel.org> escreveu: > This is a note to let you know that I've just added the patch titled > > RAS: Report all ARM processor CPER information to userspace > > to the 6.18-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… > > The filename of the patch is: > ras-report-all-arm-processor-cper-information-to-use.patch > and it can be found in the queue-6.18 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable(a)vger.kernel.org> know about it. You should also backport this patch(*): 96b010536ee0 efi/cper: align ARM CPER type with UEFI 2.9A/2.10 specs It fixes a bug at the UEFI parser for the ARM Processor Error record: basically, the specs were not clear about how the error type should be reported. The Kernel implementation were assuming that this was an enum, but UEFI errata 2.9A make it clear that the value is a bitmap. So, basically, all kernels up to 6.18 are not parsing the field the expected way: only "Cache error" was properly reported. The other 3 types were wrong. (*) You could need to backport those patches as well: a976d790f494 efi/cper: Add a new helper function to print bitmasks 8ad2c72e21ef efi/cper: Adjust infopfx size to accept an extra space Regards, Mauro Thanks, Mauro

1 week, 4 days

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Re: Patch "block: fix cached zone reports on devices with native zone append" has been added to the 6.18-stable tree

by Damien Le Moal

On 12/15/25 09:37, Sasha Levin wrote: > This is a note to let you know that I've just added the patch titled > > block: fix cached zone reports on devices with native zone append > > to the 6.18-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… > > The filename of the patch is: > block-fix-cached-zone-reports-on-devices-with-native.patch > and it can be found in the queue-6.18 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable(a)vger.kernel.org> know about it. Sasha, This is a fix for a new feature that was queued for and is now added to 6.19. So backporting this to stable and LTS kernels is not advisable. -- Damien Le Moal Western Digital Research

1 week, 4 days

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Re: Patch "block: mq-deadline: Remove support for zone write locking" has been added to the 6.6-stable tree

by Damien Le Moal

On 12/13/25 20:09, Sasha Levin wrote: > This is a note to let you know that I've just added the patch titled > > block: mq-deadline: Remove support for zone write locking > > to the 6.6-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… > > The filename of the patch is: > block-mq-deadline-remove-support-for-zone-write-lock.patch > and it can be found in the queue-6.6 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable(a)vger.kernel.org> know about it. Sasha, Zone write locking in the mq-deadline scheduler was replaced with the generic zone write plugging in the block layer in 6.10. That was not backported as that is a new feature. So removing zone write locking in 6.6 will break support for SMR drives and other zoned block devices. Removing it from 6.6 is thus not OK. Please undo this. > commit bf2022eaa2291ad1243b0711d5bd03ba4105ffbb > Author: Damien Le Moal <dlemoal(a)kernel.org> > Date: Mon Apr 8 10:41:21 2024 +0900 > > block: mq-deadline: Remove support for zone write locking > > [ Upstream commit fde02699c242e88a71286677d27cc890a959b67f ] > > With the block layer generic plugging of write operations for zoned > block devices, mq-deadline, or any other scheduler, can only ever > see at most one write operation per zone at any time. There is thus no > sequentiality requirements for these writes and thus no need to tightly > control the dispatching of write requests using zone write locking. > > Remove all the code that implement this control in the mq-deadline > scheduler and remove advertizing support for the > ELEVATOR_F_ZBD_SEQ_WRITE elevator feature. > > Signed-off-by: Damien Le Moal <dlemoal(a)kernel.org> > Reviewed-by: Hannes Reinecke <hare(a)suse.de> > Reviewed-by: Christoph Hellwig <hch(a)lst.de> > Reviewed-by: Bart Van Assche <bvanassche(a)acm.org> > Tested-by: Hans Holmberg <hans.holmberg(a)wdc.com> > Tested-by: Dennis Maisenbacher <dennis.maisenbacher(a)wdc.com> > Reviewed-by: Martin K. Petersen <martin.petersen(a)oracle.com> > Link: https://lore.kernel.org/r/20240408014128.205141-22-dlemoal@kernel.org > Signed-off-by: Jens Axboe <axboe(a)kernel.dk> > Stable-dep-of: d60055cf5270 ("block/mq-deadline: Switch back to a single dispatch list") > Signed-off-by: Sasha Levin <sashal(a)kernel.org> > > diff --git a/block/mq-deadline.c b/block/mq-deadline.c > index 78a8aa204c156..23638b03d7b3d 100644 > --- a/block/mq-deadline.c > +++ b/block/mq-deadline.c > @@ -102,7 +102,6 @@ struct deadline_data { > int prio_aging_expire; > > spinlock_t lock; > - spinlock_t zone_lock; > }; > > /* Maps an I/O priority class to a deadline scheduler priority. */ > @@ -157,8 +156,7 @@ deadline_latter_request(struct request *rq) > } > > /* > - * Return the first request for which blk_rq_pos() >= @pos. For zoned devices, > - * return the first request after the start of the zone containing @pos. > + * Return the first request for which blk_rq_pos() >= @pos. > */ > static inline struct request *deadline_from_pos(struct dd_per_prio *per_prio, > enum dd_data_dir data_dir, sector_t pos) > @@ -170,14 +168,6 @@ static inline struct request *deadline_from_pos(struct dd_per_prio *per_prio, > return NULL; > > rq = rb_entry_rq(node); > - /* > - * A zoned write may have been requeued with a starting position that > - * is below that of the most recently dispatched request. Hence, for > - * zoned writes, start searching from the start of a zone. > - */ > - if (blk_rq_is_seq_zoned_write(rq)) > - pos = round_down(pos, rq->q->limits.chunk_sectors); > - > while (node) { > rq = rb_entry_rq(node); > if (blk_rq_pos(rq) >= pos) { > @@ -308,36 +298,6 @@ static inline bool deadline_check_fifo(struct dd_per_prio *per_prio, > return time_is_before_eq_jiffies((unsigned long)rq->fifo_time); > } > > -/* > - * Check if rq has a sequential request preceding it. > - */ > -static bool deadline_is_seq_write(struct deadline_data *dd, struct request *rq) > -{ > - struct request *prev = deadline_earlier_request(rq); > - > - if (!prev) > - return false; > - > - return blk_rq_pos(prev) + blk_rq_sectors(prev) == blk_rq_pos(rq); > -} > - > -/* > - * Skip all write requests that are sequential from @rq, even if we cross > - * a zone boundary. > - */ > -static struct request *deadline_skip_seq_writes(struct deadline_data *dd, > - struct request *rq) > -{ > - sector_t pos = blk_rq_pos(rq); > - > - do { > - pos += blk_rq_sectors(rq); > - rq = deadline_latter_request(rq); > - } while (rq && blk_rq_pos(rq) == pos); > - > - return rq; > -} > - > /* > * For the specified data direction, return the next request to > * dispatch using arrival ordered lists. > @@ -346,40 +306,10 @@ static struct request * > deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio, > enum dd_data_dir data_dir) > { > - struct request *rq, *rb_rq, *next; > - unsigned long flags; > - > if (list_empty(&per_prio->fifo_list[data_dir])) > return NULL; > > - rq = rq_entry_fifo(per_prio->fifo_list[data_dir].next); > - if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q)) > - return rq; > - > - /* > - * Look for a write request that can be dispatched, that is one with > - * an unlocked target zone. For some HDDs, breaking a sequential > - * write stream can lead to lower throughput, so make sure to preserve > - * sequential write streams, even if that stream crosses into the next > - * zones and these zones are unlocked. > - */ > - spin_lock_irqsave(&dd->zone_lock, flags); > - list_for_each_entry_safe(rq, next, &per_prio->fifo_list[DD_WRITE], > - queuelist) { > - /* Check whether a prior request exists for the same zone. */ > - rb_rq = deadline_from_pos(per_prio, data_dir, blk_rq_pos(rq)); > - if (rb_rq && blk_rq_pos(rb_rq) < blk_rq_pos(rq)) > - rq = rb_rq; > - if (blk_req_can_dispatch_to_zone(rq) && > - (blk_queue_nonrot(rq->q) || > - !deadline_is_seq_write(dd, rq))) > - goto out; > - } > - rq = NULL; > -out: > - spin_unlock_irqrestore(&dd->zone_lock, flags); > - > - return rq; > + return rq_entry_fifo(per_prio->fifo_list[data_dir].next); > } > > /* > @@ -390,36 +320,8 @@ static struct request * > deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio, > enum dd_data_dir data_dir) > { > - struct request *rq; > - unsigned long flags; > - > - rq = deadline_from_pos(per_prio, data_dir, > - per_prio->latest_pos[data_dir]); > - if (!rq) > - return NULL; > - > - if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q)) > - return rq; > - > - /* > - * Look for a write request that can be dispatched, that is one with > - * an unlocked target zone. For some HDDs, breaking a sequential > - * write stream can lead to lower throughput, so make sure to preserve > - * sequential write streams, even if that stream crosses into the next > - * zones and these zones are unlocked. > - */ > - spin_lock_irqsave(&dd->zone_lock, flags); > - while (rq) { > - if (blk_req_can_dispatch_to_zone(rq)) > - break; > - if (blk_queue_nonrot(rq->q)) > - rq = deadline_latter_request(rq); > - else > - rq = deadline_skip_seq_writes(dd, rq); > - } > - spin_unlock_irqrestore(&dd->zone_lock, flags); > - > - return rq; > + return deadline_from_pos(per_prio, data_dir, > + per_prio->latest_pos[data_dir]); > } > > /* > @@ -525,10 +427,6 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, > rq = next_rq; > } > > - /* > - * For a zoned block device, if we only have writes queued and none of > - * them can be dispatched, rq will be NULL. > - */ > if (!rq) > return NULL; > > @@ -549,10 +447,6 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, > prio = ioprio_class_to_prio[ioprio_class]; > dd->per_prio[prio].latest_pos[data_dir] = blk_rq_pos(rq); > dd->per_prio[prio].stats.dispatched++; > - /* > - * If the request needs its target zone locked, do it. > - */ > - blk_req_zone_write_lock(rq); > rq->rq_flags |= RQF_STARTED; > return rq; > } > @@ -736,7 +630,6 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e) > dd->fifo_batch = fifo_batch; > dd->prio_aging_expire = prio_aging_expire; > spin_lock_init(&dd->lock); > - spin_lock_init(&dd->zone_lock); > > /* We dispatch from request queue wide instead of hw queue */ > blk_queue_flag_set(QUEUE_FLAG_SQ_SCHED, q); > @@ -818,12 +711,6 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, > > lockdep_assert_held(&dd->lock); > > - /* > - * This may be a requeue of a write request that has locked its > - * target zone. If it is the case, this releases the zone lock. > - */ > - blk_req_zone_write_unlock(rq); > - > prio = ioprio_class_to_prio[ioprio_class]; > per_prio = &dd->per_prio[prio]; > if (!rq->elv.priv[0]) { > @@ -855,18 +742,6 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, > */ > rq->fifo_time = jiffies + dd->fifo_expire[data_dir]; > insert_before = &per_prio->fifo_list[data_dir]; > -#ifdef CONFIG_BLK_DEV_ZONED > - /* > - * Insert zoned writes such that requests are sorted by > - * position per zone. > - */ > - if (blk_rq_is_seq_zoned_write(rq)) { > - struct request *rq2 = deadline_latter_request(rq); > - > - if (rq2 && blk_rq_zone_no(rq2) == blk_rq_zone_no(rq)) > - insert_before = &rq2->queuelist; > - } > -#endif > list_add_tail(&rq->queuelist, insert_before); > } > } > @@ -901,33 +776,8 @@ static void dd_prepare_request(struct request *rq) > rq->elv.priv[0] = NULL; > } > > -static bool dd_has_write_work(struct blk_mq_hw_ctx *hctx) > -{ > - struct deadline_data *dd = hctx->queue->elevator->elevator_data; > - enum dd_prio p; > - > - for (p = 0; p <= DD_PRIO_MAX; p++) > - if (!list_empty_careful(&dd->per_prio[p].fifo_list[DD_WRITE])) > - return true; > - > - return false; > -} > - > /* > * Callback from inside blk_mq_free_request(). > - * > - * For zoned block devices, write unlock the target zone of > - * completed write requests. Do this while holding the zone lock > - * spinlock so that the zone is never unlocked while deadline_fifo_request() > - * or deadline_next_request() are executing. This function is called for > - * all requests, whether or not these requests complete successfully. > - * > - * For a zoned block device, __dd_dispatch_request() may have stopped > - * dispatching requests if all the queued requests are write requests directed > - * at zones that are already locked due to on-going write requests. To ensure > - * write request dispatch progress in this case, mark the queue as needing a > - * restart to ensure that the queue is run again after completion of the > - * request and zones being unlocked. > */ > static void dd_finish_request(struct request *rq) > { > @@ -942,21 +792,8 @@ static void dd_finish_request(struct request *rq) > * called dd_insert_requests(). Skip requests that bypassed I/O > * scheduling. See also blk_mq_request_bypass_insert(). > */ > - if (!rq->elv.priv[0]) > - return; > - > - atomic_inc(&per_prio->stats.completed); > - > - if (blk_queue_is_zoned(q)) { > - unsigned long flags; > - > - spin_lock_irqsave(&dd->zone_lock, flags); > - blk_req_zone_write_unlock(rq); > - spin_unlock_irqrestore(&dd->zone_lock, flags); > - > - if (dd_has_write_work(rq->mq_hctx)) > - blk_mq_sched_mark_restart_hctx(rq->mq_hctx); > - } > + if (rq->elv.priv[0]) > + atomic_inc(&per_prio->stats.completed); > } > > static bool dd_has_work_for_prio(struct dd_per_prio *per_prio) > @@ -1280,7 +1117,6 @@ static struct elevator_type mq_deadline = { > .elevator_attrs = deadline_attrs, > .elevator_name = "mq-deadline", > .elevator_alias = "deadline", > - .elevator_features = ELEVATOR_F_ZBD_SEQ_WRITE, > .elevator_owner = THIS_MODULE, > }; > MODULE_ALIAS("mq-deadline-iosched"); -- Damien Le Moal Western Digital Research

1 week, 4 days

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PROBLEM: hwclock busted w/ M48T59 RTC (regression)

by Nick Bowler

Hi, After a stable kernel update, the hwclock command seems no longer functional on my SPARC system with an ST M48T59Y-70PC1 RTC: # hwclock [...long delay...] hwclock: select() to /dev/rtc0 to wait for clock tick timed out On prior kernels, there is no problem: # hwclock 2025-10-22 22:21:04.806992-04:00 I reproduced the same failure on 6.18-rc2 and bisected to this commit: commit 795cda8338eab036013314dbc0b04aae728880ab Author: Esben Haabendal <esben(a)geanix.com> Date: Fri May 16 09:23:35 2025 +0200 rtc: interface: Fix long-standing race when setting alarm This commit was backported to all current 6.x stable branches, as well as 5.15.x, so they all have the same regression. Reverting this commit on top of 6.18-rc2 corrects the problem. Let me know if you need any more info! Thanks, Nick

1 week, 4 days

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Live Design International 2025 Visitor List

by Sofia Nora

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1 week, 4 days

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[PATCH v2] ocfs2: fix kernel BUG in ocfs2_write_block

by Prithvi Tambewagh

When the filesystem is being mounted, the kernel panics while the data regarding slot map allocation to the local node, is being written to the disk. This occurs because the value of slot map buffer head block number, which should have been greater than or equal to `OCFS2_SUPER_BLOCK_BLKNO` (evaluating to 2) is less than it, indicative of disk metadata corruption. This triggers BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO) in ocfs2_write_block(), causing the kernel to panic. This is fixed by introducing an if condition block in ocfs2_update_disk_slot(), right before calling ocfs2_write_block(), which checks if `bh->b_blocknr` is lesser than `OCFS2_SUPER_BLOCK_BLKNO`; if yes, then ocfs2_error is called, which prints the error log, for debugging purposes, and the return value of ocfs2_error() is returned back to caller of ocfs2_update_disk_slot() i.e. ocfs2_find_slot(). If the return value is zero. then error code EIO is returned. Reported-by: syzbot+c818e5c4559444f88aa0(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c818e5c4559444f88aa0 Tested-by: syzbot+c818e5c4559444f88aa0(a)syzkaller.appspotmail.com Cc: stable(a)vger.kernel.org Signed-off-by: Prithvi Tambewagh <activprithvi(a)gmail.com> --- v1->v2: - Remove usage of le16_to_cpu() from ocfs2_error() - Cast bh->b_blocknr to unsigned long long - Remove type casting for OCFS2_SUPER_BLOCK_BLKNO - Fix Sparse warnings reported in v1 by kernel test robot - Update title from 'ocfs2: Fix kernel BUG in ocfs2_write_block' to 'ocfs2: fix kernel BUG in ocfs2_write_block' v1 link: https://lore.kernel.org/all/20251206154819.175479-1-activprithvi@gmail.com/… fs/ocfs2/slot_map.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/ocfs2/slot_map.c b/fs/ocfs2/slot_map.c index e544c704b583..e916a2e8f92d 100644 --- a/fs/ocfs2/slot_map.c +++ b/fs/ocfs2/slot_map.c @@ -193,6 +193,16 @@ static int ocfs2_update_disk_slot(struct ocfs2_super *osb, else ocfs2_update_disk_slot_old(si, slot_num, &bh); spin_unlock(&osb->osb_lock); + if (bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO) { + status = ocfs2_error(osb->sb, + "Invalid Slot Map Buffer Head " + "Block Number : %llu, Should be >= %d", + (unsigned long long)bh->b_blocknr, + OCFS2_SUPER_BLOCK_BLKNO); + if (!status) + return -EIO; + return status; + } status = ocfs2_write_block(osb, bh, INODE_CACHE(si->si_inode)); if (status < 0) base-commit: 24172e0d79900908cf5ebf366600616d29c9b417 -- 2.43.0

1 week, 4 days

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LDI Show 2025 Buyer Contacts

by Megan Castillo

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1 week, 4 days

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[PATCH RESEND] drm/kmb: Fix error handling in kmb_probe

by Ma Ke

kmb_probe() obtain a reference to a platform device by of_find_device_by_node(). This call increases the reference count of the returned device, which should be dropped by calling put_device() when the device is no longer needed. However, the code fails to call put_device() in several error handling paths and the normal device removal path. This could result in reference count leaks that prevent the proper cleanup of the platform device when the driver is unloaded or during error recovery. Add put_device() in all code paths where dsi_pdev is no longer needed, including error paths and the normal removal path. Found by code review. Cc: stable(a)vger.kernel.org Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display") Signed-off-by: Ma Ke <make24(a)iscas.ac.cn> --- drivers/gpu/drm/kmb/kmb_drv.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/kmb/kmb_drv.c b/drivers/gpu/drm/kmb/kmb_drv.c index 7c2eb1152fc2..9733337abe92 100644 --- a/drivers/gpu/drm/kmb/kmb_drv.c +++ b/drivers/gpu/drm/kmb/kmb_drv.c @@ -474,6 +474,8 @@ static void kmb_remove(struct platform_device *pdev) /* Unregister DSI host */ kmb_dsi_host_unregister(kmb->kmb_dsi); + if (kmb->kmb_dsi && kmb->kmb_dsi->pdev) + put_device(&kmb->kmb_dsi->pdev->dev); drm_atomic_helper_shutdown(drm); } @@ -518,17 +520,20 @@ static int kmb_probe(struct platform_device *pdev) ret = kmb_dsi_host_bridge_init(get_device(&dsi_pdev->dev)); if (ret == -EPROBE_DEFER) { - return -EPROBE_DEFER; + ret = -EPROBE_DEFER; + goto err_free2; } else if (ret) { DRM_ERROR("probe failed to initialize DSI host bridge\n"); - return ret; + goto err_free2; } /* Create DRM device */ kmb = devm_drm_dev_alloc(dev, &kmb_driver, struct kmb_drm_private, drm); - if (IS_ERR(kmb)) - return PTR_ERR(kmb); + if (IS_ERR(kmb)) { + ret = PTR_ERR(kmb); + goto err_free2; + } dev_set_drvdata(dev, &kmb->drm); @@ -577,7 +582,8 @@ static int kmb_probe(struct platform_device *pdev) err_free1: dev_set_drvdata(dev, NULL); kmb_dsi_host_unregister(kmb->kmb_dsi); - +err_free2: + put_device(&dsi_pdev->dev); return ret; } -- 2.17.1

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[tip: x86/boot] x86/acpi/boot: Correct acpi_is_processor_usable() check again

by tip-bot2 for Yazen Ghannam

The following commit has been merged into the x86/boot branch of tip: Commit-ID: adbf61cc47cb72b102682e690ad323e1eda652c2 Gitweb: https://git.kernel.org/tip/adbf61cc47cb72b102682e690ad323e1eda652c2 Author: Yazen Ghannam <yazen.ghannam(a)amd.com> AuthorDate: Tue, 11 Nov 2025 14:53:57 Committer: Ingo Molnar <mingo(a)kernel.org> CommitterDate: Sun, 14 Dec 2025 09:19:03 +01:00 x86/acpi/boot: Correct acpi_is_processor_usable() check again ACPI v6.3 defined a new "Online Capable" MADT LAPIC flag. This bit is used in conjunction with the "Enabled" MADT LAPIC flag to determine if a CPU can be enabled/hotplugged by the OS after boot. Before the new bit was defined, the "Enabled" bit was explicitly described like this (ACPI v6.0 wording provided): "If zero, this processor is unusable, and the operating system support will not attempt to use it" This means that CPU hotplug (based on MADT) is not possible. Many BIOS implementations follow this guidance. They may include LAPIC entries in MADT for unavailable CPUs, but since these entries are marked with "Enabled=0" it is expected that the OS will completely ignore these entries. However, QEMU will do the same (include entries with "Enabled=0") for the purpose of allowing CPU hotplug within the guest. Comment from QEMU function pc_madt_cpu_entry(): /* ACPI spec says that LAPIC entry for non present * CPU may be omitted from MADT or it must be marked * as disabled. However omitting non present CPU from * MADT breaks hotplug on linux. So possible CPUs * should be put in MADT but kept disabled. */ Recent Linux topology changes broke the QEMU use case. A following fix for the QEMU use case broke bare metal topology enumeration. Rework the Linux MADT LAPIC flags check to allow the QEMU use case only for guests and to maintain the ACPI spec behavior for bare metal. Remove an unnecessary check added to fix a bare metal case introduced by the QEMU "fix". [ bp: Change logic as Michal suggested. ] [ mingo: Removed misapplied -stable tag. ] Fixes: fed8d8773b8e ("x86/acpi/boot: Correct acpi_is_processor_usable() check") Fixes: f0551af02130 ("x86/topology: Ignore non-present APIC IDs in a present package") Closes: https://lore.kernel.org/r/20251024204658.3da9bf3f.michal.pecio@gmail.com Reported-by: Michal Pecio <michal.pecio(a)gmail.com> Signed-off-by: Yazen Ghannam <yazen.ghannam(a)amd.com> Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de> Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Tested-by: Michal Pecio <michal.pecio(a)gmail.com> Tested-by: Ricardo Neri <ricardo.neri-calderon(a)linux.intel.com> Link: https://lore.kernel.org/20251111145357.4031846-1-yazen.ghannam@amd.com Cc: stable(a)vger.kernel.org --- arch/x86/kernel/acpi/boot.c | 12 ++++++++---- arch/x86/kernel/cpu/topology.c | 15 --------------- 2 files changed, 8 insertions(+), 19 deletions(-) diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 9fa321a..d6138b2 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -35,6 +35,7 @@ #include <asm/smp.h> #include <asm/i8259.h> #include <asm/setup.h> +#include <asm/hypervisor.h> #include "sleep.h" /* To include x86_acpi_suspend_lowlevel */ static int __initdata acpi_force = 0; @@ -164,11 +165,14 @@ static bool __init acpi_is_processor_usable(u32 lapic_flags) if (lapic_flags & ACPI_MADT_ENABLED) return true; - if (!acpi_support_online_capable || - (lapic_flags & ACPI_MADT_ONLINE_CAPABLE)) - return true; + if (acpi_support_online_capable) + return lapic_flags & ACPI_MADT_ONLINE_CAPABLE; - return false; + /* + * QEMU expects legacy "Enabled=0" LAPIC entries to be counted as usable + * in order to support CPU hotplug in guests. + */ + return !hypervisor_is_type(X86_HYPER_NATIVE); } static int __init diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index f55ea3c..23190a7 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -27,7 +27,6 @@ #include <xen/xen.h> #include <asm/apic.h> -#include <asm/hypervisor.h> #include <asm/io_apic.h> #include <asm/mpspec.h> #include <asm/msr.h> @@ -236,20 +235,6 @@ static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present) cpuid_to_apicid[cpu] = apic_id; topo_set_cpuids(cpu, apic_id, acpi_id); } else { - u32 pkgid = topo_apicid(apic_id, TOPO_PKG_DOMAIN); - - /* - * Check for present APICs in the same package when running - * on bare metal. Allow the bogosity in a guest. - */ - if (hypervisor_is_type(X86_HYPER_NATIVE) && - topo_unit_count(pkgid, TOPO_PKG_DOMAIN, phys_cpu_present_map)) { - pr_info_once("Ignoring hot-pluggable APIC ID %x in present package.\n", - apic_id); - topo_info.nr_rejected_cpus++; - return; - } - topo_info.nr_disabled_cpus++; }

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