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Thu, 29 Aug 2024 18:38:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724956683; bh=geXkqqWUeVDb2gxcg/E5E7J1aR9O8y9hG/x2XUPypPM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HkUw/pPNnJxLjUURJlzPHQZr4Qb8F8+sAw4FaFm3KxDm5cyTpd2vqojw+bMqQhctz 2Dv+jAqBhBAjN56/JX1YaFzXs5Vvb1KLvkoah+ojUeJTvmgIBsdGJlYnLDz642TiUa TTHQ27LIQ4Ufyci7sFJqvOHVuz3R0tNHcljwMPwlPOXcCBIZBPMfRV3/0jIY8hPFyn Bz8UKEGrUnb7gEB1rzPiKBEMx0yJlh8EovcIXZlHV8vrL4gjL8FjNKEV8+a3lXZbzZ eV1Qht0taZEOkbDLmOW9A4aCOT2BC4Yz58MDvm/3DAOj/TLrXO8Hew4yVUhxPXhYwE 46SMYHOF6qaLA== From: Andrii Nakryiko To: linux-trace-kernel@vger.kernel.org, peterz@infradead.org, oleg@redhat.com Cc: rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, willy@infradead.org, surenb@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, Andrii Nakryiko Subject: [PATCH v4 5/8] perf/uprobe: split uprobe_unregister() Date: Thu, 29 Aug 2024 11:37:38 -0700 Message-ID: <20240829183741.3331213-6-andrii@kernel.org> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20240829183741.3331213-1-andrii@kernel.org> References: <20240829183741.3331213-1-andrii@kernel.org> MIME-Version: 1.0 X-Rspamd-Queue-Id: 6EE3B40013 X-Stat-Signature: i4m9cdmew7grousz1jrboydc4uef8t1e X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1724956684-682031 X-HE-Meta: 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 dnv7QWgW Tf+SsFnjFpdBK9DNwjhosIjSPnAtrbWzFLezATL0Hkl2/okYfx/tYY8eplwSz4BRM2DB0Gczbns0r6F4ncwJ/ttkkNy556KxrMr2lOjlrWAOJbYp6WklJ6U6fhoNh2ijNVuvL6PzibHti4ifCxTNb6ONN10OJ8PU8ftL1xkIYFa+5rNqhGrJ4HoSkitjs23dJRxRWfVV92EV45DgcRQ2t5YUcatp85/BX/9tsWdbCIk0IlMBA2+mFUqCRW/Dj3oXGSQ0p/XKieDW1eyiFDcUauoUqM4tgv/DdiSuqGOAXljudFiNX9C02ObvkYeB3eQvFd0AD8Z10yz/p7JXRIePoUSETnQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Peter Zijlstra With uprobe_unregister() having grown a synchronize_srcu(), it becomes fairly slow to call. Esp. since both users of this API call it in a loop. Peel off the sync_srcu() and do it once, after the loop. We also need to add uprobe_unregister_sync() into uprobe_register()'s error handling path, as we need to be careful about returning to the caller before we have a guarantee that partially attached consumer won't be called anymore. This is an unlikely slow path and this should be totally fine to be slow in the case of a failed attach. Signed-off-by: Peter Zijlstra (Intel) Co-developed-by: Andrii Nakryiko Signed-off-by: Andrii Nakryiko --- include/linux/uprobes.h | 8 +++++-- kernel/events/uprobes.c | 21 +++++++++++++------ kernel/trace/bpf_trace.c | 5 ++++- kernel/trace/trace_uprobe.c | 6 +++++- .../selftests/bpf/bpf_testmod/bpf_testmod.c | 3 ++- 5 files changed, 32 insertions(+), 11 deletions(-) diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index 29c935b0d504..e41cdae5597b 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -108,7 +108,8 @@ extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs); extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t); extern struct uprobe *uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc); extern int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool); -extern void uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc); +extern void uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc); +extern void uprobe_unregister_sync(void); extern int uprobe_mmap(struct vm_area_struct *vma); extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end); extern void uprobe_start_dup_mmap(void); @@ -157,7 +158,10 @@ uprobe_apply(struct uprobe* uprobe, struct uprobe_consumer *uc, bool add) return -ENOSYS; } static inline void -uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) +uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc) +{ +} +static inline void uprobe_unregister_sync(void) { } static inline int uprobe_mmap(struct vm_area_struct *vma) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 97e58d160647..e9b755ddf960 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1105,11 +1105,11 @@ register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) } /** - * uprobe_unregister - unregister an already registered probe. + * uprobe_unregister_nosync - unregister an already registered probe. * @uprobe: uprobe to remove * @uc: identify which probe if multiple probes are colocated. */ -void uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) +void uprobe_unregister_nosync(struct uprobe *uprobe, struct uprobe_consumer *uc) { int err; @@ -1121,12 +1121,15 @@ void uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) /* TODO : cant unregister? schedule a worker thread */ if (unlikely(err)) { uprobe_warn(current, "unregister, leaking uprobe"); - goto out_sync; + return; } put_uprobe(uprobe); +} +EXPORT_SYMBOL_GPL(uprobe_unregister_nosync); -out_sync: +void uprobe_unregister_sync(void) +{ /* * Now that handler_chain() and handle_uretprobe_chain() iterate over * uprobe->consumers list under RCU protection without holding @@ -1138,7 +1141,7 @@ void uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) */ synchronize_srcu(&uprobes_srcu); } -EXPORT_SYMBOL_GPL(uprobe_unregister); +EXPORT_SYMBOL_GPL(uprobe_unregister_sync); /** * uprobe_register - register a probe @@ -1196,7 +1199,13 @@ struct uprobe *uprobe_register(struct inode *inode, up_write(&uprobe->register_rwsem); if (ret) { - uprobe_unregister(uprobe, uc); + uprobe_unregister_nosync(uprobe, uc); + /* + * Registration might have partially succeeded, so we can have + * this consumer being called right at this time. We need to + * sync here. It's ok, it's unlikely slow path. + */ + uprobe_unregister_sync(); return ERR_PTR(ret); } diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 73c570b5988b..6b632710c98e 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3184,7 +3184,10 @@ static void bpf_uprobe_unregister(struct bpf_uprobe *uprobes, u32 cnt) u32 i; for (i = 0; i < cnt; i++) - uprobe_unregister(uprobes[i].uprobe, &uprobes[i].consumer); + uprobe_unregister_nosync(uprobes[i].uprobe, &uprobes[i].consumer); + + if (cnt) + uprobe_unregister_sync(); } static void bpf_uprobe_multi_link_release(struct bpf_link *link) diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 7eb79e0a5352..f7443e996b1b 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -1097,6 +1097,7 @@ static int trace_uprobe_enable(struct trace_uprobe *tu, filter_func_t filter) static void __probe_event_disable(struct trace_probe *tp) { struct trace_uprobe *tu; + bool sync = false; tu = container_of(tp, struct trace_uprobe, tp); WARN_ON(!uprobe_filter_is_empty(tu->tp.event->filter)); @@ -1105,9 +1106,12 @@ static void __probe_event_disable(struct trace_probe *tp) if (!tu->uprobe) continue; - uprobe_unregister(tu->uprobe, &tu->consumer); + uprobe_unregister_nosync(tu->uprobe, &tu->consumer); + sync = true; tu->uprobe = NULL; } + if (sync) + uprobe_unregister_sync(); } static int probe_event_enable(struct trace_event_call *call, diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index 3c0515a27842..1fc16657cf42 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -475,7 +475,8 @@ static void testmod_unregister_uprobe(void) mutex_lock(&testmod_uprobe_mutex); if (uprobe.uprobe) { - uprobe_unregister(uprobe.uprobe, &uprobe.consumer); + uprobe_unregister_nosync(uprobe.uprobe, &uprobe.consumer); + uprobe_unregister_sync(); path_put(&uprobe.path); uprobe.uprobe = NULL; }