From 57f7f81b10cf8b7f39a6d163ca9042cb0a2bb1ef Mon Sep 17 00:00:00 2001 From: John Ogness Date: Fri, 18 Dec 2020 11:40:08 +0000 Subject: printk: introduce a kmsg_dump iterator Rather than store the iterator information into the registered kmsg_dump structure, create a separate iterator structure. The kmsg_dump_iter structure can reside on the stack of the caller, thus allowing lockless use of the kmsg_dump functions. This is in preparation for removal of @logbuf_lock. Signed-off-by: John Ogness Signed-off-by: Sebastian Andrzej Siewior --- arch/powerpc/kernel/nvram_64.c | 12 +++--- arch/powerpc/platforms/powernv/opal-kmsg.c | 3 +- arch/powerpc/xmon/xmon.c | 6 +-- arch/um/kernel/kmsg_dump.c | 5 ++- drivers/hv/vmbus_drv.c | 5 ++- drivers/mtd/mtdoops.c | 5 ++- fs/pstore/platform.c | 5 ++- include/linux/kmsg_dump.h | 43 +++++++++++--------- kernel/debug/kdb/kdb_main.c | 10 ++--- kernel/printk/printk.c | 65 ++++++++++++++---------------- 10 files changed, 84 insertions(+), 75 deletions(-) diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c index 532f22637783..1ef55f4b389a 100644 --- a/arch/powerpc/kernel/nvram_64.c +++ b/arch/powerpc/kernel/nvram_64.c @@ -73,7 +73,8 @@ static const char *nvram_os_partitions[] = { }; static void oops_to_nvram(struct kmsg_dumper *dumper, - enum kmsg_dump_reason reason); + enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter); static struct kmsg_dumper nvram_kmsg_dumper = { .dump = oops_to_nvram @@ -643,7 +644,8 @@ void __init nvram_init_oops_partition(int rtas_partition_exists) * partition. If that's too much, go back and capture uncompressed text. */ static void oops_to_nvram(struct kmsg_dumper *dumper, - enum kmsg_dump_reason reason) + enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter) { struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf; static unsigned int oops_count = 0; @@ -681,13 +683,13 @@ static void oops_to_nvram(struct kmsg_dumper *dumper, return; if (big_oops_buf) { - kmsg_dump_get_buffer(dumper, false, + kmsg_dump_get_buffer(iter, false, big_oops_buf, big_oops_buf_sz, &text_len); rc = zip_oops(text_len); } if (rc != 0) { - kmsg_dump_rewind(dumper); - kmsg_dump_get_buffer(dumper, false, + kmsg_dump_rewind(iter); + kmsg_dump_get_buffer(iter, false, oops_data, oops_data_sz, &text_len); err_type = ERR_TYPE_KERNEL_PANIC; oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION); diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c index 6c3bc4b4da98..ec862846bc82 100644 --- a/arch/powerpc/platforms/powernv/opal-kmsg.c +++ b/arch/powerpc/platforms/powernv/opal-kmsg.c @@ -20,7 +20,8 @@ * message, it just ensures that OPAL completely flushes the console buffer. */ static void kmsg_dump_opal_console_flush(struct kmsg_dumper *dumper, - enum kmsg_dump_reason reason) + enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter) { /* * Outside of a panic context the pollers will continue to run, diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index 2872b66d9fec..9406b4c9cd17 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -3002,7 +3002,7 @@ print_address(unsigned long addr) static void dump_log_buf(void) { - struct kmsg_dumper dumper = { .active = 1 }; + struct kmsg_dumper_iter iter = { .active = 1 }; unsigned char buf[128]; size_t len; @@ -3014,9 +3014,9 @@ dump_log_buf(void) catch_memory_errors = 1; sync(); - kmsg_dump_rewind_nolock(&dumper); + kmsg_dump_rewind_nolock(&iter); xmon_start_pagination(); - while (kmsg_dump_get_line_nolock(&dumper, false, buf, sizeof(buf), &len)) { + while (kmsg_dump_get_line_nolock(&iter, false, buf, sizeof(buf), &len)) { buf[len] = '\0'; printf("%s", buf); } diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c index e4abac6c9727..f38349ad00ea 100644 --- a/arch/um/kernel/kmsg_dump.c +++ b/arch/um/kernel/kmsg_dump.c @@ -6,7 +6,8 @@ #include static void kmsg_dumper_stdout(struct kmsg_dumper *dumper, - enum kmsg_dump_reason reason) + enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter) { static char line[1024]; struct console *con; @@ -25,7 +26,7 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper, return; printf("kmsg_dump:\n"); - while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len)) { + while (kmsg_dump_get_line(iter, true, line, sizeof(line), &len)) { line[len] = '\0'; printf("%s", line); } diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index e99400f3ae1d..db39c96bbf43 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -1359,7 +1359,8 @@ static void vmbus_isr(void) * buffer and call into Hyper-V to transfer the data. */ static void hv_kmsg_dump(struct kmsg_dumper *dumper, - enum kmsg_dump_reason reason) + enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter) { size_t bytes_written; phys_addr_t panic_pa; @@ -1374,7 +1375,7 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper, * Write dump contents to the page. No need to synchronize; panic should * be single-threaded. */ - kmsg_dump_get_buffer(dumper, false, hv_panic_page, HV_HYP_PAGE_SIZE, + kmsg_dump_get_buffer(iter, false, hv_panic_page, HV_HYP_PAGE_SIZE, &bytes_written); if (bytes_written) hyperv_report_panic_msg(panic_pa, bytes_written); diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c index 774970bfcf85..6bc2c728adb7 100644 --- a/drivers/mtd/mtdoops.c +++ b/drivers/mtd/mtdoops.c @@ -267,7 +267,8 @@ static void find_next_position(struct mtdoops_context *cxt) } static void mtdoops_do_dump(struct kmsg_dumper *dumper, - enum kmsg_dump_reason reason) + enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter) { struct mtdoops_context *cxt = container_of(dumper, struct mtdoops_context, dump); @@ -276,7 +277,7 @@ static void mtdoops_do_dump(struct kmsg_dumper *dumper, if (reason == KMSG_DUMP_OOPS && !dump_oops) return; - kmsg_dump_get_buffer(dumper, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE, + kmsg_dump_get_buffer(iter, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE, record_size - MTDOOPS_HEADER_SIZE, NULL); if (reason != KMSG_DUMP_OOPS) { diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index ce03c3dbb5c3..5c2c14d5f6fc 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -384,7 +384,8 @@ void pstore_record_init(struct pstore_record *record, * end of the buffer. */ static void pstore_dump(struct kmsg_dumper *dumper, - enum kmsg_dump_reason reason) + enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter) { unsigned long total = 0; const char *why; @@ -434,7 +435,7 @@ static void pstore_dump(struct kmsg_dumper *dumper, dst_size -= header_size; /* Write dump contents. */ - if (!kmsg_dump_get_buffer(dumper, true, dst + header_size, + if (!kmsg_dump_get_buffer(iter, true, dst + header_size, dst_size, &dump_size)) break; diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h index 4095a34db0fa..2fdb10ab1799 100644 --- a/include/linux/kmsg_dump.h +++ b/include/linux/kmsg_dump.h @@ -29,6 +29,18 @@ enum kmsg_dump_reason { KMSG_DUMP_MAX }; +/** + * struct kmsg_dumper_iter - iterator for kernel crash message dumper + * @active: Flag that specifies if this is currently dumping + * @cur_seq: Points to the oldest message to dump (private) + * @next_seq: Points after the newest message to dump (private) + */ +struct kmsg_dumper_iter { + bool active; + u64 cur_seq; + u64 next_seq; +}; + /** * struct kmsg_dumper - kernel crash message dumper structure * @list: Entry in the dumper list (private) @@ -36,37 +48,30 @@ enum kmsg_dump_reason { * through the record iterator * @max_reason: filter for highest reason number that should be dumped * @registered: Flag that specifies if this is already registered - * @active: Flag that specifies if this is currently dumping - * @cur_seq: Points to the oldest message to dump (private) - * @next_seq: Points after the newest message to dump (private) */ struct kmsg_dumper { struct list_head list; - void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason); + void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason, + struct kmsg_dumper_iter *iter); enum kmsg_dump_reason max_reason; - bool active; bool registered; - - /* private state of the kmsg iterator */ - u64 cur_seq; - u64 next_seq; }; #ifdef CONFIG_PRINTK void kmsg_dump(enum kmsg_dump_reason reason); -bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, +bool kmsg_dump_get_line_nolock(struct kmsg_dumper_iter *iter, bool syslog, char *line, size_t size, size_t *len); -bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, +bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog, char *line, size_t size, size_t *len); -bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, +bool kmsg_dump_get_buffer(struct kmsg_dumper_iter *iter, bool syslog, char *buf, size_t size, size_t *len_out); -void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper); +void kmsg_dump_rewind_nolock(struct kmsg_dumper_iter *iter); -void kmsg_dump_rewind(struct kmsg_dumper *dumper); +void kmsg_dump_rewind(struct kmsg_dumper_iter *dumper_iter); int kmsg_dump_register(struct kmsg_dumper *dumper); @@ -78,30 +83,30 @@ static inline void kmsg_dump(enum kmsg_dump_reason reason) { } -static inline bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, +static inline bool kmsg_dump_get_line_nolock(struct kmsg_dumper_iter *iter, bool syslog, const char *line, size_t size, size_t *len) { return false; } -static inline bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, +static inline bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog, const char *line, size_t size, size_t *len) { return false; } -static inline bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, +static inline bool kmsg_dump_get_buffer(struct kmsg_dumper_iter *iter, bool syslog, char *buf, size_t size, size_t *len) { return false; } -static inline void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) +static inline void kmsg_dump_rewind_nolock(struct kmsg_dumper_iter *iter) { } -static inline void kmsg_dump_rewind(struct kmsg_dumper *dumper) +static inline void kmsg_dump_rewind(struct kmsg_dumper_iter *iter) { } diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 4e09fab52faf..048baadd7a41 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -2157,7 +2157,7 @@ static int kdb_dmesg(int argc, const char **argv) int adjust = 0; int n = 0; int skip = 0; - struct kmsg_dumper dumper = { .active = 1 }; + struct kmsg_dumper_iter iter = { .active = 1 }; size_t len; char buf[201]; @@ -2182,8 +2182,8 @@ static int kdb_dmesg(int argc, const char **argv) kdb_set(2, setargs); } - kmsg_dump_rewind_nolock(&dumper); - while (kmsg_dump_get_line_nolock(&dumper, 1, NULL, 0, NULL)) + kmsg_dump_rewind_nolock(&iter); + while (kmsg_dump_get_line_nolock(&iter, 1, NULL, 0, NULL)) n++; if (lines < 0) { @@ -2215,8 +2215,8 @@ static int kdb_dmesg(int argc, const char **argv) if (skip >= n || skip < 0) return 0; - kmsg_dump_rewind_nolock(&dumper); - while (kmsg_dump_get_line_nolock(&dumper, 1, buf, sizeof(buf), &len)) { + kmsg_dump_rewind_nolock(&iter); + while (kmsg_dump_get_line_nolock(&iter, 1, buf, sizeof(buf), &len)) { if (skip) { skip--; continue; diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 986fc9fad210..b992be31824f 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3394,6 +3394,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_reason_str); */ void kmsg_dump(enum kmsg_dump_reason reason) { + struct kmsg_dumper_iter iter; struct kmsg_dumper *dumper; unsigned long flags; @@ -3413,25 +3414,21 @@ void kmsg_dump(enum kmsg_dump_reason reason) continue; /* initialize iterator with data about the stored records */ - dumper->active = true; - + iter.active = true; logbuf_lock_irqsave(flags); - dumper->cur_seq = latched_seq_read_nolock(&clear_seq); - dumper->next_seq = prb_next_seq(prb); + iter.cur_seq = latched_seq_read_nolock(&clear_seq); + iter.next_seq = prb_next_seq(prb); logbuf_unlock_irqrestore(flags); /* invoke dumper which will iterate over records */ - dumper->dump(dumper, reason); - - /* reset iterator */ - dumper->active = false; + dumper->dump(dumper, reason, &iter); } rcu_read_unlock(); } /** * kmsg_dump_get_line_nolock - retrieve one kmsg log line (unlocked version) - * @dumper: registered kmsg dumper + * @iter: kmsg dumper iterator * @syslog: include the "<4>" prefixes * @line: buffer to copy the line to * @size: maximum size of the buffer @@ -3448,7 +3445,7 @@ void kmsg_dump(enum kmsg_dump_reason reason) * * The function is similar to kmsg_dump_get_line(), but grabs no locks. */ -bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, +bool kmsg_dump_get_line_nolock(struct kmsg_dumper_iter *iter, bool syslog, char *line, size_t size, size_t *len) { struct printk_info info; @@ -3459,16 +3456,16 @@ bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, prb_rec_init_rd(&r, &info, line, size); - if (!dumper->active) + if (!iter->active) goto out; /* Read text or count text lines? */ if (line) { - if (!prb_read_valid(prb, dumper->cur_seq, &r)) + if (!prb_read_valid(prb, iter->cur_seq, &r)) goto out; l = record_print_text(&r, syslog, printk_time); } else { - if (!prb_read_valid_info(prb, dumper->cur_seq, + if (!prb_read_valid_info(prb, iter->cur_seq, &info, &line_count)) { goto out; } @@ -3477,7 +3474,7 @@ bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog, } - dumper->cur_seq = r.info->seq + 1; + iter->cur_seq = r.info->seq + 1; ret = true; out: if (len) @@ -3487,7 +3484,7 @@ out: /** * kmsg_dump_get_line - retrieve one kmsg log line - * @dumper: registered kmsg dumper + * @iter: kmsg dumper iterator * @syslog: include the "<4>" prefixes * @line: buffer to copy the line to * @size: maximum size of the buffer @@ -3502,14 +3499,14 @@ out: * A return value of FALSE indicates that there are no more records to * read. */ -bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, +bool kmsg_dump_get_line(struct kmsg_dumper_iter *iter, bool syslog, char *line, size_t size, size_t *len) { unsigned long flags; bool ret; logbuf_lock_irqsave(flags); - ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len); + ret = kmsg_dump_get_line_nolock(iter, syslog, line, size, len); logbuf_unlock_irqrestore(flags); return ret; @@ -3518,7 +3515,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_line); /** * kmsg_dump_get_buffer - copy kmsg log lines - * @dumper: registered kmsg dumper + * @iter: kmsg dumper iterator * @syslog: include the "<4>" prefixes * @buf: buffer to copy the line to * @size: maximum size of the buffer @@ -3535,7 +3532,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_line); * A return value of FALSE indicates that there are no more records to * read. */ -bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, +bool kmsg_dump_get_buffer(struct kmsg_dumper_iter *iter, bool syslog, char *buf, size_t size, size_t *len_out) { struct printk_info info; @@ -3547,19 +3544,19 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, bool ret = false; bool time = printk_time; - if (!dumper->active || !buf || !size) + if (!iter->active || !buf || !size) goto out; logbuf_lock_irqsave(flags); - if (prb_read_valid_info(prb, dumper->cur_seq, &info, NULL)) { - if (info.seq != dumper->cur_seq) { + if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) { + if (info.seq != iter->cur_seq) { /* messages are gone, move to first available one */ - dumper->cur_seq = info.seq; + iter->cur_seq = info.seq; } } /* last entry */ - if (dumper->cur_seq >= dumper->next_seq) { + if (iter->cur_seq >= iter->next_seq) { logbuf_unlock_irqrestore(flags); goto out; } @@ -3570,7 +3567,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, * because this function (by way of record_print_text()) will * not write more than size-1 bytes of text into @buf. */ - seq = find_first_fitting_seq(dumper->cur_seq, dumper->next_seq, + seq = find_first_fitting_seq(iter->cur_seq, iter->next_seq, size - 1, syslog, time); /* @@ -3583,7 +3580,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, len = 0; prb_for_each_record(seq, prb, seq, &r) { - if (r.info->seq >= dumper->next_seq) + if (r.info->seq >= iter->next_seq) break; len += record_print_text(&r, syslog, time); @@ -3592,7 +3589,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, prb_rec_init_rd(&r, &info, buf + len, size - len); } - dumper->next_seq = next_seq; + iter->next_seq = next_seq; ret = true; logbuf_unlock_irqrestore(flags); out: @@ -3604,7 +3601,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); /** * kmsg_dump_rewind_nolock - reset the iterator (unlocked version) - * @dumper: registered kmsg dumper + * @iter: kmsg dumper iterator * * Reset the dumper's iterator so that kmsg_dump_get_line() and * kmsg_dump_get_buffer() can be called again and used multiple @@ -3612,26 +3609,26 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); * * The function is similar to kmsg_dump_rewind(), but grabs no locks. */ -void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) +void kmsg_dump_rewind_nolock(struct kmsg_dumper_iter *iter) { - dumper->cur_seq = latched_seq_read_nolock(&clear_seq); - dumper->next_seq = prb_next_seq(prb); + iter->cur_seq = latched_seq_read_nolock(&clear_seq); + iter->next_seq = prb_next_seq(prb); } /** * kmsg_dump_rewind - reset the iterator - * @dumper: registered kmsg dumper + * @iter: kmsg dumper iterator * * Reset the dumper's iterator so that kmsg_dump_get_line() and * kmsg_dump_get_buffer() can be called again and used multiple * times within the same dumper.dump() callback. */ -void kmsg_dump_rewind(struct kmsg_dumper *dumper) +void kmsg_dump_rewind(struct kmsg_dumper_iter *iter) { unsigned long flags; logbuf_lock_irqsave(flags); - kmsg_dump_rewind_nolock(dumper); + kmsg_dump_rewind_nolock(iter); logbuf_unlock_irqrestore(flags); } EXPORT_SYMBOL_GPL(kmsg_dump_rewind); -- cgit v1.2.1