kernel/linux.git/drivers/ptp/ptp_vclock.c, branch linux-7.1.y

ptp: vclock: Switch from RCU to SRCU

2026-06-04T01:58:54+00:00

The usage of PTP vClocks leads immediately to the following issues with ptp4l with LOCKDEP and DEBUG_ATOMIC_SLEEP enabled: "BUG: sleeping function called from invalid context". ptp_convert_timestamp() acquires a mutex_t within a RCU read section. This is illegal, because acquiring a mutex_t can result in voluntary scheduling request which is not allowed within a RCU read section. Replace the RCU usage with SRCU where sleeping is allowed. Reported-by: Florian Zeitz Closes: https://lore.kernel.org/all/00a8cce8-410e-4038-98af-49be6d93d7bd@schettke.com/ Fixes: 67d93ffc0f3c ("ptp: vclock: use mutex to fix "sleep on atomic" bug") Signed-off-by: Kurt Kanzenbach Reviewed-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20260529-vclock_rcu-v2-1-02a5531fab92@linutronix.de Signed-off-by: Jakub Kicinski

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

ptp: prevent possible ABBA deadlock in ptp_clock_freerun()

2025-08-12T21:17:35+00:00

syzbot reported the following ABBA deadlock: CPU0 CPU1 ---- ---- n_vclocks_store() lock(&ptp->n_vclocks_mux) [1] (physical clock) pc_clock_adjtime() lock(&clk->rwsem) [2] (physical clock) ... ptp_clock_freerun() ptp_vclock_in_use() lock(&ptp->n_vclocks_mux) [3] (physical clock) ptp_clock_unregister() posix_clock_unregister() lock(&clk->rwsem) [4] (virtual clock) Since ptp virtual clock is registered only under ptp physical clock, both ptp_clock and posix_clock must be physical clocks for ptp_vclock_in_use() to lock &ptp->n_vclocks_mux and check ptp->n_vclocks. However, when unregistering vclocks in n_vclocks_store(), the locking ptp->n_vclocks_mux is a physical clock lock, but clk->rwsem of ptp_clock_unregister() called through device_for_each_child_reverse() is a virtual clock lock. Therefore, clk->rwsem used in CPU0 and clk->rwsem used in CPU1 are different locks, but in lockdep, a false positive occurs because the possibility of deadlock is determined through lock-class. To solve this, lock subclass annotation must be added to the posix_clock rwsem of the vclock. Reported-by: syzbot+7cfb66a237c4a5fb22ad@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7cfb66a237c4a5fb22ad Fixes: 73f37068d540 ("ptp: support ptp physical/virtual clocks conversion") Signed-off-by: Jeongjun Park Acked-by: Richard Cochran Reviewed-by: Vladimir Oltean Link: https://patch.msgid.link/20250728062649.469882-1-aha310510@gmail.com Signed-off-by: Jakub Kicinski

time/timecounter: Fix the lie that struct cyclecounter is const

2025-07-01T13:38:25+00:00

In both the read callback for struct cyclecounter, and in struct timecounter, struct cyclecounter is declared as a const pointer. Unfortunatly, a number of users of this pointer treat it as a non-const pointer as it is burried in a larger structure that is heavily modified by the callback function when accessed. This lie had been hidden by the fact that container_of() "casts away" a const attribute of a pointer without any compiler warning happening at all. Fix this all up by removing the const attribute in the needed places so that everyone can see that the structure really isn't const, but can, and is, modified by the users of it. Signed-off-by: Greg Kroah-Hartman Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/2025070124-backyard-hurt-783a@gregkh

ptp: make ptp_class constant

2024-03-11T20:42:09+00:00

Since commit 43a7206b0963 ("driver core: class: make class_register() take a const *"), the driver core allows for struct class to be in read-only memory, so move the ptp_class structure to be declared at build time placing it into read-only memory, instead of having to be dynamically allocated at boot time. Suggested-by: Greg Kroah-Hartman Signed-off-by: Ricardo B. Marliere Reviewed-by: Simon Horman Link: https://lore.kernel.org/r/20240305-ptp-v1-1-ed253eb33c20@marliere.net Signed-off-by: Jakub Kicinski

ptp: vclock: use mutex to fix "sleep on atomic" bug

2023-02-23T05:23:48+00:00

vclocks were using spinlocks to protect access to its timecounter and cyclecounter. Access to timecounter/cyclecounter is backed by the same driver callbacks that are used for non-virtual PHCs, but the usage of the spinlock imposes a new limitation that didn't exist previously: now they're called in atomic context so they mustn't sleep. Some drivers like sfc or ice may sleep on these callbacks, causing errors like "BUG: scheduling while atomic: ptp5/25223/0x00000002" Fix it replacing the vclock's spinlock by a mutex. It fix the mentioned bug and it doesn't introduce longer delays. I've tested synchronizing various different combinations of clocks: - vclock->sysclock - sysclock->vclock - vclock->vclock - hardware PHC in different NIC -> vclock - created 4 vclocks and launch 4 parallel phc2sys processes with lockdep enabled In all cases, comparing the delays reported by phc2sys, they are in the same range of values than before applying the patch. Link: https://lore.kernel.org/netdev/69d0ff33-bd32-6aa5-d36c-fbdc3c01337c@redhat.com/ Fixes: 5d43f951b1ac ("ptp: add ptp virtual clock driver framework") Reported-by: Yalin Li Suggested-by: Richard Cochran Tested-by: Miroslav Lichvar Signed-off-by: Íñigo Huguet Acked-by: Richard Cochran Link: https://lore.kernel.org/r/20230221130616.21837-1-ihuguet@redhat.com Signed-off-by: Jakub Kicinski

ptp: Speed up vclock lookup

2022-05-10T07:48:09+00:00

ptp_convert_timestamp() is called in the RX path of network messages. The current implementation takes ~5000ns on 1.2GHz A53. This is too much for the hot path of packet processing. Introduce hash table for fast vclock lookup in ptp_convert_timestamp(). The execution time of ptp_convert_timestamp() is reduced to ~700ns on 1.2GHz A53. Signed-off-by: Gerhard Engleder Acked-by: Richard Cochran Signed-off-by: Paolo Abeni

ptp: Pass hwtstamp to ptp_convert_timestamp()

2022-05-10T07:48:08+00:00

ptp_convert_timestamp() converts only the timestamp hwtstamp, which is a field of the argument with the type struct skb_shared_hwtstamps *. So a pointer to the hwtstamp field of this structure is sufficient. Rework ptp_convert_timestamp() to use an argument of type ktime_t *. This allows to add additional timestamp manipulation stages before the call of ptp_convert_timestamp(). Signed-off-by: Gerhard Engleder Acked-by: Richard Cochran Signed-off-by: Paolo Abeni

ptp: Add cycles support for virtual clocks

2022-05-10T07:48:08+00:00

ptp vclocks require a free running time for their timecounter. Currently only a physical clock forced to free running is supported. If vclocks are used, then the physical clock cannot be synchronized anymore. The synchronized time is not available in hardware in this case. As a result, timed transmission with TAPRIO hardware support is not possible anymore. If hardware would support a free running time additionally to the physical clock, then the physical clock does not need to be forced to free running. Thus, the physical clocks can still be synchronized while vclocks are in use. The physical clock could be used to synchronize the time domain of the TSN network and trigger TAPRIO. In parallel vclocks can be used to synchronize other time domains. Introduce support for a free running cycle counter called cycles to physical clocks. Rework ptp vclocks to use this free running cycle counter. Default implementation is based on time of physical clock. Thus, behavior of ptp vclocks based on physical clocks without free running cycle counter is identical to previous behavior. Signed-off-by: Gerhard Engleder Acked-by: Richard Cochran Signed-off-by: Paolo Abeni