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Wed, 24 Sep 2025 13:50:13 -0700 (PDT) MIME-Version: 1.0 References: <20250924115124.194940-1-wangjinchao600@gmail.com> <20250924115124.194940-7-wangjinchao600@gmail.com> In-Reply-To: <20250924115124.194940-7-wangjinchao600@gmail.com> From: Marco Elver Date: Wed, 24 Sep 2025 22:49:35 +0200 X-Gm-Features: AS18NWBgUAm60x7jbnTDK3WCQpUXDCFu_1mbN9k4BD6qrp1olQW-5h-0n2U9Y9E Message-ID: Subject: Re: [PATCH v5 06/23] mm/ksw: add singleton /proc/kstackwatch interface To: Jinchao Wang Cc: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Randy Dunlap , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Kees Cook , Alice Ryhl , Sami Tolvanen , Miguel Ojeda , Masahiro Yamada , Rong Xu , Naveen N Rao , David Kaplan , Andrii Nakryiko , Jinjie Ruan , Nam Cao , workflows@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, Andrey Ryabinin , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com, "David S. Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: 9udbkhhcrfy5qd44g8rdxq8bgyzhc84p X-Rspamd-Queue-Id: D5B562000F X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1758747014-605957 X-HE-Meta: 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 D+eQZ6rv PJ75B/WHHGcjKetHSATMfhrGwTiXM+zgJV3058+b0UxOAjDXx4YQ+9m82IKW9M4nuXOeetl+DWc6mERhFsthmO0DbrtMJRMBiT8qpAz614UJJm5H7aknkZf1uJZze2yo3Fb9QkwqrxYoCEb33nmNlV6oCCfAzWSO4rAznuoDcoxonR3d2IqxNuOmk9fiWi3oY3VHrtNbh5d7EafTCvbBvToa+zoyaaeVdP5jvxGcQ67hI0UQ5M7HBPpqMhz5AA4tX3i23BIY+N1gukjRxl6XLljG/8b7qOkcbaJysUG2CPjQZXmTdvyXn+q3cQ9zNMclDflAlFTTVL5qbiNdn+ps4d2s3HW2Nr8oy2iSzckbu1DU/ABPleRLK2YAn1A== 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: On Wed, 24 Sept 2025 at 13:51, Jinchao Wang wrote: > > Provide the /proc/kstackwatch file to read or update the configuration. > Only a single process can open this file at a time, enforced using atomic > config_file_busy, to prevent concurrent access. Why is this in /proc and not debugfs? > ksw_get_config() exposes the configuration pointer as const. > > Signed-off-by: Jinchao Wang > --- > mm/kstackwatch/kernel.c | 77 +++++++++++++++++++++++++++++++++++- > mm/kstackwatch/kstackwatch.h | 3 ++ > 2 files changed, 79 insertions(+), 1 deletion(-) > > diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c > index 3b7009033dd4..4a06ddadd9c7 100644 > --- a/mm/kstackwatch/kernel.c > +++ b/mm/kstackwatch/kernel.c > @@ -3,11 +3,15 @@ > > #include > #include > +#include > +#include > #include > +#include > > #include "kstackwatch.h" > > static struct ksw_config *ksw_config; > +static atomic_t config_file_busy = ATOMIC_INIT(0); > > struct param_map { > const char *name; /* long name */ > @@ -74,7 +78,7 @@ static int ksw_parse_param(struct ksw_config *config, const char *key, > * - sp_offset |so (u16) : offset from stack pointer at func_offset > * - watch_len |wl (u16) : watch length (1,2,4,8) > */ > -static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) > +static int ksw_parse_config(char *buf, struct ksw_config *config) > { > char *part, *key, *val; > int ret; > @@ -109,18 +113,89 @@ static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) > return 0; > } > > +static ssize_t kstackwatch_proc_write(struct file *file, > + const char __user *buffer, size_t count, > + loff_t *pos) > +{ > + char input[MAX_CONFIG_STR_LEN]; > + int ret; > + > + if (count == 0 || count >= sizeof(input)) > + return -EINVAL; > + > + if (copy_from_user(input, buffer, count)) > + return -EFAULT; > + > + input[count] = '\0'; > + strim(input); > + > + if (!strlen(input)) { > + pr_info("config cleared\n"); > + return count; > + } > + > + ret = ksw_parse_config(input, ksw_config); > + if (ret) { > + pr_err("Failed to parse config %d\n", ret); > + return ret; > + } > + > + return count; > +} > + > +static int kstackwatch_proc_show(struct seq_file *m, void *v) > +{ > + seq_printf(m, "%s\n", ksw_config->user_input); > + return 0; > +} > + > +static int kstackwatch_proc_open(struct inode *inode, struct file *file) > +{ > + if (atomic_cmpxchg(&config_file_busy, 0, 1)) > + return -EBUSY; > + > + return single_open(file, kstackwatch_proc_show, NULL); > +} > + > +static int kstackwatch_proc_release(struct inode *inode, struct file *file) > +{ > + atomic_set(&config_file_busy, 0); > + return single_release(inode, file); > +} > + > +static const struct proc_ops kstackwatch_proc_ops = { > + .proc_open = kstackwatch_proc_open, > + .proc_read = seq_read, > + .proc_write = kstackwatch_proc_write, > + .proc_lseek = seq_lseek, > + .proc_release = kstackwatch_proc_release, > +}; > + > +const struct ksw_config *ksw_get_config(void) > +{ > + return ksw_config; > +} > static int __init kstackwatch_init(void) > { > ksw_config = kzalloc(sizeof(*ksw_config), GFP_KERNEL); > if (!ksw_config) > return -ENOMEM; > > + if (!proc_create("kstackwatch", 0600, NULL, &kstackwatch_proc_ops)) { > + pr_err("create proc kstackwatch fail"); > + kfree(ksw_config); > + return -ENOMEM; > + } > + > pr_info("module loaded\n"); > return 0; > } > > static void __exit kstackwatch_exit(void) > { > + remove_proc_entry("kstackwatch", NULL); > + kfree(ksw_config->func_name); > + kfree(ksw_config->user_input); > kfree(ksw_config); > > pr_info("module unloaded\n"); > diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h > index a7bad207f863..983125d5cf18 100644 > --- a/mm/kstackwatch/kstackwatch.h > +++ b/mm/kstackwatch/kstackwatch.h > @@ -29,4 +29,7 @@ struct ksw_config { > char *user_input; > }; > > +// singleton, only modified in kernel.c > +const struct ksw_config *ksw_get_config(void); > + > #endif /* _KSTACKWATCH_H */ > -- > 2.43.0 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To view this discussion visit https://groups.google.com/d/msgid/kasan-dev/20250924115124.194940-7-wangjinchao600%40gmail.com.