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ring buffer: handle shmp errors
[lttng-ust.git] / libringbuffer / backend_internal.h
diff --git a/libringbuffer/backend_internal.h b/libringbuffer/backend_internal.h
index 7bd5c738936084a0ed84fec4fa822a44211812f7..9edd2e59f8b348bc5f8352e589d3499fcb0f476d 100644 (file)
--- a/libringbuffer/backend_internal.h
+++ b/libringbuffer/backend_internal.h
@@ -203,17 +203,23 @@ int subbuffer_id_check_index(const struct lttng_ust_lib_ring_buffer_config *conf
 #ifdef LTTNG_RING_BUFFER_COUNT_EVENTS
 static inline
 void subbuffer_count_record(const struct lttng_ust_lib_ring_buffer_config *config,
+                           const struct lttng_ust_lib_ring_buffer_ctx *ctx,
                            struct lttng_ust_lib_ring_buffer_backend *bufb,
                            unsigned long idx, struct lttng_ust_shm_handle *handle)
 {
-       unsigned long sb_bindex;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 
-       sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
-       v_inc(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_commit);
+       backend_pages = lib_ring_buffer_get_backend_pages_from_ctx(config, ctx);
+       if (caa_unlikely(!backend_pages)) {
+               if (lib_ring_buffer_backend_get_pages(config, ctx, &backend_pages))
+                       return;
+       }
+       v_inc(config, &backend_pages->records_commit);
 }
 #else /* LTTNG_RING_BUFFER_COUNT_EVENTS */
 static inline
 void subbuffer_count_record(const struct lttng_ust_lib_ring_buffer_config *config,
+                           const struct lttng_ust_lib_ring_buffer_ctx *ctx,
                            struct lttng_ust_lib_ring_buffer_backend *bufb,
                            unsigned long idx, struct lttng_ust_shm_handle *handle)
 {
@@ -230,12 +236,23 @@ void subbuffer_consume_record(const struct lttng_ust_lib_ring_buffer_config *con
                              struct lttng_ust_shm_handle *handle)
 {
        unsigned long sb_bindex;
+       struct channel *chan;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages_shmp;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 
        sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
-       CHAN_WARN_ON(shmp(handle, bufb->chan),
-                    !v_read(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_unread));
+       chan = shmp(handle, bufb->chan);
+       if (!chan)
+               return;
+       pages_shmp = shmp_index(handle, bufb->array, sb_bindex);
+       if (!pages_shmp)
+               return;
+       backend_pages = shmp(handle, pages_shmp->shmp);
+       if (!backend_pages)
+               return;
+       CHAN_WARN_ON(chan, !v_read(config, &backend_pages->records_unread));
        /* Non-atomic decrement protected by exclusive subbuffer access */
-       _v_dec(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_unread);
+       _v_dec(config, &backend_pages->records_unread);
        v_inc(config, &bufb->records_read);
 }
 
@@ -247,9 +264,21 @@ unsigned long subbuffer_get_records_count(
                                struct lttng_ust_shm_handle *handle)
 {
        unsigned long sb_bindex;
+       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 
-       sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
-       return v_read(config, &shmp(handle, shmp_index(handle, bufb->array, sb_bindex)->shmp)->records_commit);
+       wsb = shmp_index(handle, bufb->buf_wsb, idx);
+       if (!wsb)
+               return 0;
+       sb_bindex = subbuffer_id_get_index(config, wsb->id);
+       rpages = shmp_index(handle, bufb->array, sb_bindex);
+       if (!rpages)
+               return 0;
+       backend_pages = shmp(handle, rpages->shmp);
+       if (!backend_pages)
+               return 0;
+       return v_read(config, &backend_pages->records_commit);
 }
 
 /*
@@ -266,15 +295,25 @@ unsigned long subbuffer_count_records_overrun(
                                unsigned long idx,
                                struct lttng_ust_shm_handle *handle)
 {
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
        unsigned long overruns, sb_bindex;
+       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 
-       sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
-       pages = shmp_index(handle, bufb->array, sb_bindex);
-       overruns = v_read(config, &shmp(handle, pages->shmp)->records_unread);
-       v_set(config, &shmp(handle, pages->shmp)->records_unread,
-             v_read(config, &shmp(handle, pages->shmp)->records_commit));
-       v_set(config, &shmp(handle, pages->shmp)->records_commit, 0);
+       wsb = shmp_index(handle, bufb->buf_wsb, idx);
+       if (!wsb)
+               return 0;
+       sb_bindex = subbuffer_id_get_index(config, wsb->id);
+       rpages = shmp_index(handle, bufb->array, sb_bindex);
+       if (!rpages)
+               return 0;
+       backend_pages = shmp(handle, rpages->shmp);
+       if (!backend_pages)
+               return 0;
+       overruns = v_read(config, &backend_pages->records_unread);
+       v_set(config, &backend_pages->records_unread,
+             v_read(config, &backend_pages->records_commit));
+       v_set(config, &backend_pages->records_commit, 0);
 
        return overruns;
 }
@@ -286,12 +325,22 @@ void subbuffer_set_data_size(const struct lttng_ust_lib_ring_buffer_config *conf
                             unsigned long data_size,
                             struct lttng_ust_shm_handle *handle)
 {
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
        unsigned long sb_bindex;
+       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 
-       sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
-       pages = shmp_index(handle, bufb->array, sb_bindex);
-       shmp(handle, pages->shmp)->data_size = data_size;
+       wsb = shmp_index(handle, bufb->buf_wsb, idx);
+       if (!wsb)
+               return;
+       sb_bindex = subbuffer_id_get_index(config, wsb->id);
+       rpages = shmp_index(handle, bufb->array, sb_bindex);
+       if (!rpages)
+               return;
+       backend_pages = shmp(handle, rpages->shmp);
+       if (!backend_pages)
+               return;
+       backend_pages->data_size = data_size;
 }
 
 static inline
@@ -300,12 +349,18 @@ unsigned long subbuffer_get_read_data_size(
                                struct lttng_ust_lib_ring_buffer_backend *bufb,
                                struct lttng_ust_shm_handle *handle)
 {
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
        unsigned long sb_bindex;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages_shmp;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 
        sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
-       pages = shmp_index(handle, bufb->array, sb_bindex);
-       return shmp(handle, pages->shmp)->data_size;
+       pages_shmp = shmp_index(handle, bufb->array, sb_bindex);
+       if (!pages_shmp)
+               return 0;
+       backend_pages = shmp(handle, pages_shmp->shmp);
+       if (!backend_pages)
+               return 0;
+       return backend_pages->data_size;
 }
 
 static inline
@@ -315,12 +370,22 @@ unsigned long subbuffer_get_data_size(
                                unsigned long idx,
                                struct lttng_ust_shm_handle *handle)
 {
-       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *pages;
        unsigned long sb_bindex;
+       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+       struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
 
-       sb_bindex = subbuffer_id_get_index(config, shmp_index(handle, bufb->buf_wsb, idx)->id);
-       pages = shmp_index(handle, bufb->array, sb_bindex);
-       return shmp(handle, pages->shmp)->data_size;
+       wsb = shmp_index(handle, bufb->buf_wsb, idx);
+       if (!wsb)
+               return 0;
+       sb_bindex = subbuffer_id_get_index(config, wsb->id);
+       rpages = shmp_index(handle, bufb->array, sb_bindex);
+       if (!rpages)
+               return 0;
+       backend_pages = shmp(handle, rpages->shmp);
+       if (!backend_pages)
+               return 0;
+       return backend_pages->data_size;
 }
 
 static inline
@@ -328,7 +393,12 @@ void subbuffer_inc_packet_count(const struct lttng_ust_lib_ring_buffer_config *c
                struct lttng_ust_lib_ring_buffer_backend *bufb,
                unsigned long idx, struct lttng_ust_shm_handle *handle)
 {
-       shmp_index(handle, bufb->buf_cnt, idx)->seq_cnt++;
+       struct lttng_ust_lib_ring_buffer_backend_counts *counts;
+
+       counts = shmp_index(handle, bufb->buf_cnt, idx);
+       if (!counts)
+               return;
+       counts->seq_cnt++;
 }
 
 /**
@@ -342,6 +412,7 @@ void lib_ring_buffer_clear_noref(const struct lttng_ust_lib_ring_buffer_config *
                                 struct lttng_ust_shm_handle *handle)
 {
        unsigned long id, new_id;
+       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
 
        if (config->mode != RING_BUFFER_OVERWRITE)
                return;
@@ -350,7 +421,10 @@ void lib_ring_buffer_clear_noref(const struct lttng_ust_lib_ring_buffer_config *
         * Performing a volatile access to read the sb_pages, because we want to
         * read a coherent version of the pointer and the associated noref flag.
         */
-       id = CMM_ACCESS_ONCE(shmp_index(handle, bufb->buf_wsb, idx)->id);
+       wsb = shmp_index(handle, bufb->buf_wsb, idx);
+       if (!wsb)
+               return;
+       id = CMM_ACCESS_ONCE(wsb->id);
        for (;;) {
                /* This check is called on the fast path for each record. */
                if (caa_likely(!subbuffer_id_is_noref(config, id))) {
@@ -364,7 +438,7 @@ void lib_ring_buffer_clear_noref(const struct lttng_ust_lib_ring_buffer_config *
                }
                new_id = id;
                subbuffer_id_clear_noref(config, &new_id);
-               new_id = uatomic_cmpxchg(&shmp_index(handle, bufb->buf_wsb, idx)->id, id, new_id);
+               new_id = uatomic_cmpxchg(&wsb->id, id, new_id);
                if (caa_likely(new_id == id))
                        break;
                id = new_id;
@@ -381,9 +455,15 @@ void lib_ring_buffer_set_noref_offset(const struct lttng_ust_lib_ring_buffer_con
                                      unsigned long idx, unsigned long offset,
                                      struct lttng_ust_shm_handle *handle)
 {
+       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
+       struct channel *chan;
+
        if (config->mode != RING_BUFFER_OVERWRITE)
                return;
 
+       wsb = shmp_index(handle, bufb->buf_wsb, idx);
+       if (!wsb)
+               return;
        /*
         * Because ring_buffer_set_noref() is only called by a single thread
         * (the one which updated the cc_sb value), there are no concurrent
@@ -395,14 +475,16 @@ void lib_ring_buffer_set_noref_offset(const struct lttng_ust_lib_ring_buffer_con
         * subbuffer_set_noref() uses a volatile store to deal with concurrent
         * readers of the noref flag.
         */
-       CHAN_WARN_ON(shmp(handle, bufb->chan),
-                    subbuffer_id_is_noref(config, shmp_index(handle, bufb->buf_wsb, idx)->id));
+       chan = shmp(handle, bufb->chan);
+       if (!chan)
+               return;
+       CHAN_WARN_ON(chan, subbuffer_id_is_noref(config, wsb->id));
        /*
         * Memory barrier that ensures counter stores are ordered before set
         * noref and offset.
         */
        cmm_smp_mb();
-       subbuffer_id_set_noref_offset(config, &shmp_index(handle, bufb->buf_wsb, idx)->id, offset);
+       subbuffer_id_set_noref_offset(config, &wsb->id, offset);
 }
 
 /**
@@ -416,16 +498,23 @@ int update_read_sb_index(const struct lttng_ust_lib_ring_buffer_config *config,
                         unsigned long consumed_count,
                         struct lttng_ust_shm_handle *handle)
 {
+       struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
        unsigned long old_id, new_id;
 
+       wsb = shmp_index(handle, bufb->buf_wsb, consumed_idx);
+       if (caa_unlikely(!wsb))
+               return -EPERM;
+
        if (config->mode == RING_BUFFER_OVERWRITE) {
+               struct channel *chan;
+
                /*
                 * Exchange the target writer subbuffer with our own unused
                 * subbuffer. No need to use CMM_ACCESS_ONCE() here to read the
                 * old_wpage, because the value read will be confirmed by the
                 * following cmpxchg().
                 */
-               old_id = shmp_index(handle, bufb->buf_wsb, consumed_idx)->id;
+               old_id = wsb->id;
                if (caa_unlikely(!subbuffer_id_is_noref(config, old_id)))
                        return -EAGAIN;
                /*
@@ -435,18 +524,19 @@ int update_read_sb_index(const struct lttng_ust_lib_ring_buffer_config *config,
                if (caa_unlikely(!subbuffer_id_compare_offset(config, old_id,
                                                          consumed_count)))
                        return -EAGAIN;
-               CHAN_WARN_ON(shmp(handle, bufb->chan),
-                            !subbuffer_id_is_noref(config, bufb->buf_rsb.id));
+               chan = shmp(handle, bufb->chan);
+               if (caa_unlikely(!chan))
+                       return -EPERM;
+               CHAN_WARN_ON(chan, !subbuffer_id_is_noref(config, bufb->buf_rsb.id));
                subbuffer_id_set_noref_offset(config, &bufb->buf_rsb.id,
                                              consumed_count);
-               new_id = uatomic_cmpxchg(&shmp_index(handle, bufb->buf_wsb, consumed_idx)->id, old_id,
-                                bufb->buf_rsb.id);
+               new_id = uatomic_cmpxchg(&wsb->id, old_id, bufb->buf_rsb.id);
                if (caa_unlikely(old_id != new_id))
                        return -EAGAIN;
                bufb->buf_rsb.id = new_id;
        } else {
                /* No page exchange, use the writer page directly */
-               bufb->buf_rsb.id = shmp_index(handle, bufb->buf_wsb, consumed_idx)->id;
+               bufb->buf_rsb.id = wsb->id;
        }
        return 0;
 }
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