Pstore dmesg write 篇

  1. 在需要dump kmsg的情景，如 reboot、oops和panic，调用kmsg_dumper。 kmsg_dumper通过遍历，将数据发给每个dumper。

        

void kmsg_dump(enum kmsg_dump_reason reason){struct kmsg_dumper *dumper;        rcu_read_lock();list_for_each_entry_rcu(dumper, &dump_list, list) {                dumper->dump(dumper, reason);        }         rcu_read_unlock();}

  2. pstore 的 dumper函数

     

static void pstore_dump(struct kmsg_dumper * dumper,enum kmsg_dump_reason reason){/* 获取 dump 原因 */why = get_reason_str(reason);oopscount++;while (total < kmsg_bytes) {if (big_oops_buf && is_lock) {/* 进行压缩 */dst = big_oops_buf;/* 获取数据 */if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,size, &len))break;/* 压缩数据 */zipped_len = pstore_compress(dst, psinfo->buf,hsize + len, psinfo->bufsize);if (zipped_len > 0) {} else {/* 压缩不成功 */compressed = false;total_len = copy_kmsg_to_buffer(hsize, len);}} else {/* 非压缩 */dst = psinfo->buf;hsize = sprintf(dst, "%s#%d Partu%\n", why, oopscount,part);size = psinfo->bufsize - hsize;dst += hsize;/* 获取数据 */if (!kmsg_dump_get_buffer(dumper, true, dst,size, &len))break;compressed = false;total_len = hsize + len;}/* 写入Pstore前段，如ramoops */ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,oopscount, compressed, total_len, psinfo);if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())pstore_new_entry = 1; // for timertotal += total_len;part++;}}

3. write 写入存储区

static int pstore_write_compat(enum pstore_type_id type,       enum kmsg_dump_reason reason,       u64 *id, unsigned int part, int count,       bool compressed, size_t size,       struct pstore_info *psi){return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,     size, psi);}

static int notrace ramoops_pstore_write_buf(enum pstore_type_id,enum kmsg_dump_reason reason,u64 * id, unsigned int part,const char * buf,bool compressed, size_t size,struct pstore_info * psi){struct ramoops_context * cxt = psi->data;struct persistent_ram_zone * prz;size_t hlen;/* 写入 console、ftrace、pmsg 到 pstore */if (type == PSTORE_TYPE_CONSOLE) {persistent_ram_write(cxt->cprz, buf, size);} else if (type == PSTORE_TYPE_FTRACE) {} else if (type == PSTORE_TYPE_PMSG) {}/* 写入DMESG */if (type != PSTORE_TYPE_DMESG)return -EINVAL;prz = cxt->przs[cxt->dump_write_cnt];hlen = ramoops_write_kmsg_hdr(prz, compressed);if (size + hlen > prz->buffer_size)size = prz->buffer_size - hlen;persistent_ram_write(prz, buf, size);cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;return 0;}

int notrace persistent_ram_write(struct persistent_ram_zone * prz,const void * s, unsigned int count){int rem;int c = count;size_t start;/* 计算需要的大小 */buffer_size_add(prz, c);/* 获取本次存储开始的位置 */start = buffer_start_add(prz, c);/* 计算从当前位置可以存储的大小 */rem = prz->buffer_size - start;if (unlikely(rem < c)) {/* 如果无法完全存储则覆盖之前的存储set start = 0 */persistent_ram_update(prz, s, start, rem);s += rem;c -= rem;start = 0;}/* 存储数据 */persistent_ram_update(prz, s, start, c);/* 更新头部校验码 ECC */persistent_ram_update_header_ecc(prz);}

static void notrace persistent_ram_update(struct persistent_ram_zone * prz,const void * s, unsigned int start, unsigned int count){struct persistent_ram_buffer * buffer = prz->buffer;memcpy_toio(buffer->data + start, s, count);persistent_ram_update_ecc(prz, start, count);}