From e006858f1a1c6e8ba8aeff67e9b15700f70174da Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Mon, 11 Mar 2024 18:23:07 +0200 Subject: nexthop: Fix splat with CONFIG_DEBUG_PREEMPT=y Locally generated packets can increment the new nexthop statistics from process context, resulting in the following splat [1] due to preemption being enabled. Fix by using get_cpu_ptr() / put_cpu_ptr() which will which take care of disabling / enabling preemption. BUG: using smp_processor_id() in preemptible [00000000] code: ping/949 caller is nexthop_select_path+0xcf8/0x1e30 CPU: 12 PID: 949 Comm: ping Not tainted 6.8.0-rc7-custom-gcb450f605fae #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014 Call Trace: dump_stack_lvl+0xbd/0xe0 check_preemption_disabled+0xce/0xe0 nexthop_select_path+0xcf8/0x1e30 fib_select_multipath+0x865/0x18b0 fib_select_path+0x311/0x1160 ip_route_output_key_hash_rcu+0xe54/0x2720 ip_route_output_key_hash+0x193/0x380 ip_route_output_flow+0x25/0x130 raw_sendmsg+0xbab/0x34a0 inet_sendmsg+0xa2/0xe0 __sys_sendto+0x2ad/0x430 __x64_sys_sendto+0xe5/0x1c0 do_syscall_64+0xc5/0x1d0 entry_SYSCALL_64_after_hwframe+0x63/0x6b [...] Fixes: f4676ea74b85 ("net: nexthop: Add nexthop group entry stats") Signed-off-by: Ido Schimmel Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20240311162307.545385-5-idosch@nvidia.com Signed-off-by: Jakub Kicinski --- net/ipv4/nexthop.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/ipv4/nexthop.c') diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c index 4c6915bff31e..74928a9d1aa4 100644 --- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c @@ -674,10 +674,11 @@ static void nh_grp_entry_stats_inc(struct nh_grp_entry *nhge) { struct nh_grp_entry_stats *cpu_stats; - cpu_stats = this_cpu_ptr(nhge->stats); + cpu_stats = get_cpu_ptr(nhge->stats); u64_stats_update_begin(&cpu_stats->syncp); u64_stats_inc(&cpu_stats->packets); u64_stats_update_end(&cpu_stats->syncp); + put_cpu_ptr(cpu_stats); } static void nh_grp_entry_stats_read(struct nh_grp_entry *nhge, -- cgit v1.2.3-59-g8ed1b